High resolution systems, kits, apparatus, and methods using magnetic beads for high throughput microbiology applications

ABSTRACT

A method of transferring material from a first microfabricated device to a second microfabricated device. At least one magnetic bead is loaded into at least one microwell of the first microfabricated device, where a plurality of cells are cultivated. The second microfabricated device is positioned such that the at least one microwell of the first array of microwells is aligned with at least one microwell of the second array of microwells. A magnetic field is applied so as to move the at least one magnetic bead contained in the at least one microwell of the first microfabricated device into the at least one microwell of the second microfabricated device. In this manner, at least one cell from the plurality of cells in the at least one microwell of the first microfabricated device is transferred to the at least one microwell of the second microfabricated device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Nonprovisional patentapplication Ser. No. 15/135,377, filed on Apr. 21, 2016, which claimsthe benefit of U.S. Provisional Patent Application No. 62/299,088 filedFeb. 24, 2016, U.S. Provisional Patent Application No. 62/292,091 filedFeb. 5, 2016, and U.S. Provisional Patent Application No. 62/150,677filed Apr. 21, 2015. This application also claims the benefit of U.S.Provisional Patent Application No. 62/357,142, filed on Jun. 30, 2016.The disclosure of each of these prior-filed applications is incorporatedby reference herein in its entirety.

INCORPORATION OF SEQUENCE LISTING

This application includes a Sequence Listing which has been submitted inASCII format via EFS-Web, named “GALT_006_US_ST25.txt,” which is 3 KB insize and created on Sep. 17, 2017. The contents of the Sequence Listingwere present in the application as originally filed and are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to innovations in microbiology,microfabrication, chemistry, optics, robotics, and informationtechnology. More specifically, the present disclosure relates tosystems, apparatus, kits, and methods for high throughput cultivation,screening, isolation, sampling, and/or identification of biologicalentities and/or nutrients.

BACKGROUND

Traditional techniques and tools for cultivating biological entitiesfrom environmental and other samples are often slow, laborious, andexpensive. Even with these techniques and tools, often cells and otherbiological entities still defy all attempts at culture, resulting inmissed information and/or product opportunities. Likewise, the screeningof a population of biological entities for a particular metabolite,enzyme, protein, nucleic acid, phenotype, mutation, metabolic pathway,gene, adaptation, capability, and/or therapeutic benefit is challenging,requiring complex and expensive methods. For example, microbes live inextremely high-risk environments. To survive, microbes have developedamazing sets of biochemical tools, including novel enzymes, uniquemetabolites, innovative genetic pathways, and strategies formanipulating their environment and their microbial neighbors—powerfulsolutions that could lead to new insights and products ranging fromlife-saving antibiotics to fertilizers that improve food production andsecurity.

SUMMARY

The present disclosure provides microbiology systems, apparatus, kits,and methods for streamlining the cultivation workflow, supporting highthroughput screening, and/or developing new insights and products inaccordance with some embodiments. For example, an apparatus may comprisea microfabricated device for receiving a sample comprising one or morecells. The microfabricated device defines a high density array ofmicrowells for cultivating one or more cells.

In some embodiments, a method of transferring material from a firstmicrofabricated device including a first array of microwells to a secondmicrofabricated device including a second array of microwells, isprovided. The method includes: loading at least one magnetic bead intoat least one microwell of the first array of microwells; incubating thefirst microfabricated device to cultivate a plurality of cells in atleast one microwell of the first array of microwells; positioning thesecond microfabricated device relative to the first microfabricateddevice such that the at least one microwell of the first array ofmicrowells of the first microfabricated device is aligned with at leastone microwell of the second array of microwells of the secondmicrofabricated device; and applying a magnetic field (e.g., by usingpermanent magnet or an electromagnet) so as to move the at least onemagnetic bead contained in the at least one microwell of the first arrayof microwells into the at least one microwell of the second array ofmicrowells, whereby at least one cell from the plurality of cells in theat least one microwell of the first array of microwells is transferredto the at least one microwell of the second array of microwells.

In some embodiments, the method further includes: prior to incubatingthe first microfabricated device, preparing the first microfabricateddevice such that at least one microwell of the first array of microwellsincludes at least one cell and at least one magnetic bead, whereinincubating the first microfabricated device comprises cultivating aplurality of cells in the at least one microwell of the firstmicrofabricated device from the at least one cell. In some of theseembodiments, preparing the first microfabricated device includes loadinga magnetic bead solution including a solvent and at least one magneticbead into the at least one microwell; and loading at least one cell intothe at least one microwell. A magnet can be used to draw the at leastone magnetic bead to the inside of the at least one microwell, and thesolvent can be allowed to evaporate. Preparing the first microfabricateddevice can include loading into the at least one microwell a samplesolution that includes at least one magnetic bead and at least one cell.A membrane can be further applied to the microfabricated device to sealthe at least one microwell after the bead(s) and cell(s) are loaded.

In some embodiments, each of the first and second microfabricateddevices includes an upper surface, and positioning the secondmicrofabricated device relative to the first microfabricated device canbe by positioning the upper surface of the second microfabricated deviceopposing and apart from the upper surface of the first microfabricateddevice.

In some embodiments, each of the first and second microfabricateddevices comprises an upper surface, and positioning the secondmicrofabricated device relative to the first microfabricated devicecomprises positioning the upper surface of the second microfabricateddevice opposing and in contact with the upper surface of the firstmicrofabricated device.

In some embodiments, prior to applying the magnetic field, a liquidlayer is applied on the at least one microwell of the first array ofmicrowells of the first microfabricated device. The liquid layer can bea layer immiscible with water (e.g., an oil layer), an aqueous layer, orother layer.

In some embodiments, the method further includes obtaining a genomic DNAfrom the at least one cell which has been transferred into the at leastone microwell of the second microfabricated device, and amplifying thegenomic DNA sequence using polymerase chain reaction in the at least onemicrowell of the second microfabricated device in the presence of thetransferred at least one magnetic bead.

In some embodiments, a method of transferring material from a firstmicrofabricated device including a first array of microwells to a secondmicrofabricated device including a second array of microwells, isprovided. The method includes: preparing the first microfabricateddevice such that at least one microwell of the first array of microwellsincludes a material of interest and at least one magnetic bead;positioning the second microfabricated device relative to the firstmicrofabricated device such that the at least one microwell of the firstarray of microwells of the first microfabricated device is aligned withat least one microwell of the second array of microwells of the secondmicrofabricated device; and applying a magnetic field so as to move theat least one magnetic bead contained in the at least one microwell ofthe first array of microwells into the at least one microwell of thesecond array of microwells, whereby at least a portion of the materialof interest in the at least one microwell of the first array ofmicrowells is transferred to the at least one microwell of the secondarray of microwells. The material of interest can be a biologicalentity, e.g., it can include a plurality of cells. Preparing the firstmicrofabricated device can include: providing the at least one microwellof the first array of microwells with at least one cell and at least onemagnetic bead; and prior to applying the magnetic field, incubating thefirst microfabricated device to grow a plurality of cells from theprovided at least one cell in the at least one microwell of the firstmicrofabricated device. Providing the at least one microwell of thefirst array of microwells with at least one cell and at least onemagnetic bead can include: loading a magnetic bead solution including asolvent and at least one magnetic bead into the at least one microwell;and loading at least one cell into the at least one microwell. The atleast one magnetic bead can be loaded into the microwell with a samplesolution which also includes at least one cell.

In some embodiments, a method of transferring material from a firstmicrofabricated device to a second microfabricated device. The firstmicrofabricated device includes a first array of microwells and thesecond microfabricated device includes a second array of microwells. Atleast one microwell of the first array of microwells of the firstfabricated device includes at least one magnetic bead. The methodincludes: providing a material of interest into the at least onemicrowell which comprises the at least one magnetic bead; positioningthe second microfabricated device relative to the first microfabricateddevice such that the at least one microwell of the first array ofmicrowells of the first microfabricated device is aligned with at leastone microwell of the second array of microwells of the secondmicrofabricated device; and applying a magnetic field so as to move theat least one magnetic bead contained in the at least one microwell ofthe first array of microwells into the at least one microwell of thesecond array of microwells, whereby at least a portion of the materialof interest in the at least one microwell of the first array ofmicrowells is transferred to the at least one microwell of the secondarray of microwells.

In some embodiments, a method of transferring material from a firstmicrofabricated device to a second microfabricated device. The firstmicrofabricated device includes a first array of microwells and thesecond microfabricated device includes a second array of microwells. Atleast one microwell of the first array of microwells of the firstfabricated device includes at least one magnetic bead and at least onecell. The method includes positioning the second microfabricated devicerelative to the first microfabricate chip such that the at least onemicrowell of the first array of microwells of the first microfabricateddevice is aligned with at least one microwell of the second array ofmicrowells of the second microfabricated device; and applying a magneticfield so as to move the at least one magnetic bead contained in the atleast one microwell of the first array of microwells into the at leastone microwell of the second array of microwells, whereby at least aportion of the material of interest in the at least one microwell of thefirst array of microwells is transferred to the at least one microwellof the second array of microwells.

In some embodiments, a kit is provided, which includes a firstmicrofabricated device including a first array of microwells, at leastone microwell of which includes at least one magnetic bead. The kit canfurther include a membrane suitable for applying on the firstmicrofabricated device to seal the at least one microwell. The kit canfurther include a second microfabricated device including a second arrayof microwells, wherein each microwell of the first array of microwellscan be aligned with a microwell of the second array of microwells.

In some embodiments, a kit is provided, which includes a microfabricateddevice including a high density array of microwells, and a solutionincluding a solvent and a plurality of magnetic beads. The kit canfurther include a membrane suitable for applying on the firstmicrofabricated device to seal the at least one microwell. The kit canalso include a magnet.

In the above methods of transfer of material between chips usingmagnetic bead(s) and kits including magnetic bead(s), the membrane canbe one of gas-permeable, liquid-permeable, and impermeable. The firstmicrofabricated device (and/or the second microfabricated device) canhave a surface density of microwells of at least 150 microwells per cm²,at least 250 microwells per cm², at least 400 microwells per cm², atleast 500 microwells per cm², at least 750 microwells per cm², at least1,000 microwells per cm², at least 2,500 microwells per cm², at least5,000 microwells per cm², at least 7,500 microwells per cm², at least10,000 microwells per cm², at least 50,000 microwells per cm², at least100,000 microwells per cm², or at least 160,000 per cm². Each microwellof the first (and/or the second) array of microwells of the firstmicrofabricated device can have a diameter of from about 5 μm to about500 from about 10 μm to about 300 or from about 20 μm to about 200 μm.

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the inventive subject matter disclosed herein. In particular, allcombinations of claimed subject matter appearing at the end of thisdisclosure are contemplated as being part of the inventive subjectmatter disclosed herein. It should also be appreciated that terminologyexplicitly employed herein that also may appear in any disclosureincorporated by reference should be accorded a meaning most consistentwith the particular concepts disclosed herein.

Other systems, processes, and features will become apparent to thoseskilled in the art upon examination of the following drawings anddetailed description. It is intended that all such additional systems,processes, and features be included within this description, be withinthe scope of the present invention, and be protected by the accompanyingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled artisan will understand that the drawings primarily are forillustrative purposes and are not intended to limit the scope of theinventive subject matter described herein. The drawings are notnecessarily to scale; in some instances, various aspects of theinventive subject matter disclosed herein may be shown exaggerated orenlarged in the drawings to facilitate an understanding of differentfeatures. In the drawings, like reference characters generally refer tolike features (e.g., functionally similar and/or structurally similarelements).

FIG. 1 is a perspective view illustrating a microfabricated device orchip in accordance with some embodiments.

FIGS. 2A-2C are top, side, and end views, respectively, illustratingdimensions of microfabricated device or chip in accordance with someembodiments.

FIGS. 3A and 3B are exploded and top views, respectively, illustrating amicrofabricated device or chip in accordance with some embodiments.

FIGS. 4A and 4B are diagrams illustrating a membrane in accordance withsome embodiments. FIG. 4C is an image of a membrane surface withimpressions formed from contact with an array of wells in accordancewith some embodiments.

FIG. 5A is a flowchart illustrating a method for isolating cells from asample in accordance with some embodiments. FIG. 5B is a diagramillustrating a method for isolating cells from a soil sample inaccordance with some embodiments.

FIG. 6 is a flowchart illustrating a method for isolating andcultivating cells from a sample in accordance with some embodiments.

FIG. 7 is a diagram illustrating a method for isolating and cultivatingcells from a complex sample in accordance with some embodiments. Panel716 shows the output: isolated strains of cultivated cells (SEQ ID NOs:2-6).

FIGS. 8A-8C are diagrams illustrating picking by one pin or multiplepins in accordance with some embodiments.

FIGS. 9A-9D are images demonstrating picking of a well in accordancewith some embodiments.

FIGS. 10A-10D are diagrams illustrating a tool for picking a chip inaccordance with some embodiments.

FIG. 11 is an image of a well that has been picked through a thin layerof agar, illustrating picking through a membrane or sealing layer inaccordance with some embodiments.

FIG. 12 is a diagram illustrating a cross-section of a chip 1200 inaccordance with some embodiments.

FIG. 13 is a flowchart illustrating methods for screening in accordancewith some embodiments.

FIG. 14 is a diagram illustrating a screening method in accordance withsome embodiments.

FIG. 15 is a series of images illustrating a screening example inaccordance with some embodiments.

FIGS. 16A-16C are images illustrating recovery from a screen inaccordance with some embodiments.

FIG. 17A is an exploded diagram illustrating a chip for screening inaccordance with some embodiments. FIG. 17B is a fluorescence image of achip following screening in accordance with some embodiments. FIG. 17Cis an image showing a process of picking a sample from the chipfollowing screening in accordance with some embodiments.

FIG. 18 is a flowchart illustrating a counting method in accordance withsome embodiments.

FIG. 19 is a diagram illustrating a counting method in accordance withsome embodiments. Panel 1916 shows the output: sequences and relativeabundance of cultivated cells (SEQ ID NOs: 2-6).

FIG. 20 is a diagram illustrating an indexing system in accordance withsome embodiments.

FIGS. 21A-21E are diagrams illustrating a chip with well-specificchemistries in accordance with some embodiments.

FIG. 22 is a diagram illustrating transfer using magnetic beads inaccordance with some embodiments.

FIGS. 23A-23C are images illustrating a transfer of material usingmagnetic beads in accordance with some embodiments.

FIG. 24A is a microscopic image of a source chip containing magneticbeads;

FIG. 24B is a microscopic image of a destination chip (which isinitially empty) after transfer of magnetic beads.

FIGS. 25A-25C illustrate an example on how two chips are aligned fortransferring material therebetween with the assistance of magneticbeads.

FIG. 26A shows magnetic beads in different closed-spaced microwells of asource chip to be transferred to a destination chip without crossover;FIG. 26B shows the magnetic beads in FIG. 26A are transferred tocorresponding microwells of a destination chip without crossover; FIG.26C shows magnetic beads in different closed-spaced microwells of asource chip to be transferred to a destination chip with crossover; FIG.26D shows the magnetic beads in FIG. 26C are transferred to microwellsof a destination chip with crossover.

FIG. 27A is a microscopic image of a source chip with microwells loadedwith E coli; FIG. 27B is a microscopic image of the source chip aftersome E. coli has been transferred to another chip using magnetic beads;FIG. 27C is a microscopic image of the destination containing E. colitransferred from the source chip using magnetic beads and further grown.

FIG. 28 is gel electrophoresis result of on-chip PCR product of a gDNAin the presence of various amounts of magnetic beads according to someembodiments of the present disclosure.

FIG. 29 is gel electrophoresis result of a series of PCR productsobtained from different conditions according to some embodiments of thepresent disclosure.

FIG. 30 is gel electrophoresis result of on-chip PCR product of amixture of three different species in the presence of magnetic beadsaccording to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to systems, kits, apparatus,and methods for isolation, culturing, adaptation, sampling, and/orscreening of biological entities and/or nutrients. A microfabricateddevice (or a “chip”) is disclosed for receiving a sample comprising atleast one biological entity (e.g., at least one cell). The term“biological entity” may include, but is not limited to, an organism, acell, a cell component, a cell product, and a virus, and the term“species” may be used to describe a unit of classification, including,but not limited to, an operational taxonomic unit (OTU), a genotype, aphylotype, a phenotype, an ecotype, a history, a behavior orinteraction, a product, a variant, and an evolutionarily significantunit.

A cell may be Archaea, Bacteria, or Eukaryota (e.g., fungi). Forexample, a cell may be a microorganism, such as an aerobic, anaerobic,or facultative aerobic microorganisms. A virus may be a bacteriophage.Other cell components/products may include, but are not limited to,proteins, amino acids, enzymes, saccharides, adenosine triphosphate(ATP), lipids, nucleic acids (e.g., DNA and RNA), nucleosides,nucleotides, cell membranes/walls, flagella, fimbriae, organelles,metabolites, vitamins, hormones, neurotransmitters, and antibodies.

A nutrient may be defined (e.g., a chemically defined or syntheticmedium) or undefined (e.g., a basal or complex medium). A nutrient mayinclude or be a component of a laboratory-formulated and/or acommercially manufactured medium (e.g., a mix of two or more chemicals).A nutrient may include or be a component of a liquid nutrient medium(i.e., a nutrient broth), such as a marine broth, a lysogeny broth(e.g., Luria broth), etc. A nutrient may include or be a component of aliquid medium mixed with agar to form a solid medium and/or acommercially available manufactured agar plate, such as blood agar.

A nutrient may include or be a component of selective media. Forexample, selective media may be used for the growth of only certainbiological entities or only biological entities with certain properties(e.g., antibiotic resistance or synthesis of a certain metabolite). Anutrient may include or be a component of differential media todistinguish one type of biological entity from another type ofbiological entity or other types of biological entities by usingbiochemical characteristics in the presence of specific indicator (e.g.,neutral red, phenol red, eosin y, or methylene blue).

A nutrient may include or be a component of an extract of or mediaderived from a natural environment. For example, a nutrient may bederived from an environment natural to a particular type of biologicalentity, a different environment, or a plurality of environments. Theenvironment may include, but is not limited to, one or more of abiological tissue (e.g., connective, muscle, nervous, epithelial, plantepidermis, vascular, ground, etc.), a biological fluid or otherbiological product (e.g., amniotic fluid, bile, blood, cerebrospinalfluid, cerumen, exudate, fecal matter, gastric fluid, interstitialfluid, intracellular fluid, lymphatic fluid, milk, mucus, rumen content,saliva, sebum, semen, sweat, urine, vaginal secretion, vomit, etc.), amicrobial suspension, air (including, e.g., different gas contents),supercritical carbon dioxide, soil (including, e.g., minerals, organicmatter, gases, liquids, organisms, etc.), sediment (e.g., agricultural,marine, etc.), living organic matter (e.g., plants, insects, other smallorganisms and microorganisms), dead organic matter, forage (e.g.,grasses, legumes, silage, crop residue, etc.), a mineral, oil or oilproducts (e.g., animal, vegetable, petrochemical), water (e.g.,naturally-sourced freshwater, drinking water, seawater, etc.), and/orsewage (e.g., sanitary, commercial, industrial, and/or agriculturalwastewater and surface runoff).

A microfabricated device may define a high density array of microwellsfor cultivating the at least one biological entity. The term “highdensity” may refer to a capability of a system or method to distribute anumber of experiments within a constant area. For example, amicrofabricated device comprising a “high density” of experimental unitsmay include about 150 microwells per cm² to about 160,000 microwells ormore per cm², as discussed further herein. Additional examples are shownin TABLE 1.

TABLE 1 Spacing Length of side between Density of of microwellsmicrowells microwells (μm) (μm) (wells/cm2) 500 500 100 100 100 2500 10050 4489 100 10 8281 50 50 10000 50 10 27556 20 10 110889 10 5 444889 5 51000000

A microfabricated device may include a substrate with a series offunctional layers. The series of functional layers may include a firstfunctional layer defining a first array of experimental units (e.g.,wells) and at least one subsequent functional layer defining asubsequent array of experimental units (e.g., microwells) in eachexperimental unit of the preceding functional layer. Each of theexperimental units may be configured to receive and cultivate and/orscreen biological entities and/or nutrients. In particular, systems,kits, apparatus, and methods described herein may be used for automatedand/or high throughput screening of different conditions against a highdensity matrix of cells. For example, systems, kits, apparatus, andmethods described herein may be used to test and compare the effect(s)of one or more different nutrients on the growth of microorganismsand/or screen for metabolites, enzyme activity, mutations, or other cellfeatures.

FIG. 1 is a perspective view illustrating a microfabricated device orchip in accordance with some embodiments. Chip 100 includes a substrateshaped in a microscope slide format with injection-molded features ontop surface 102. The features include four separate microwell arrays (ormicroarrays) 104 as well as ejector marks 106. The microwells in eachmicroarray are arranged in a grid pattern with well-free margins aroundthe edges of chip 100 and between microarrays 104.

FIGS. 2A-2C are top, side, and end views, respectively, illustratingdimensions of chip 100 in accordance with some embodiments. In FIG. 2A,the top of chip 100 is approximately 25.5 mm by 75.5 mm. In FIG. 2B, theend of chip 100 is approximately 25.5 mm by 0.8 mm. In FIG. 2C, the sideof chip 100 is approximately 75.5 mm by 0.8 mm.

After a sample is loaded on a microfabricated device, a membrane may beapplied to at least a portion of a microfabricated device. FIG. 3A is anexploded diagram of the microfabricated device 300 shown from a top viewin FIG. 3B in accordance with some embodiments. Device 300 includes achip with an array of wells 302 holding, for example, soil microbes. Amembrane 304 is placed on top of the array of wells 302. A gasket 306 isplaced on top of the membrane 304. A polycarbonate cover 308 with fillholes 310 is placed on top of the gasket 306. Finally, sealing tape 312is applied to the cover 308.

A membrane may cover at least a portion of a microfabricated deviceincluding one or more experimental units, wells, or microwells. Forexample, after a sample is loaded on a microfabricated device, at leastone membrane may be applied to at least one microwell of a high densityarray of microwells. A plurality of membranes may be applied to aplurality of portions of a microfabricated device. For example, separatemembranes may be applied to separate subsections of a high density arrayof microwells.

A membrane may be connected, attached, partially attached, affixed,sealed, and/or partially sealed to a microfabricated device to retain atleast one biological entity in the at least one microwell of the highdensity array of microwells. For example, a membrane may be reversiblyaffixed to a microfabricated device using lamination. A membrane may bepunctured, peeled back, detached, partially detached, removed, and/orpartially removed to access at least one biological entity in the atleast one microwell of the high density array of microwells.

A portion of the population of cells in at least one experimental unit,well, or microwell may attach to a membrane (via, e.g., adsorption). Ifso, the population of cells in at least one experimental unit, well, ormicrowell may be sampled by peeling back the membrane such that theportion of the population of cells in the at least one experimentalunit, well, or microwell remains attached to the membrane.

FIGS. 4A and 4B are diagrams illustrating a membrane in accordance withsome embodiments. FIG. 4A shows a side view of a chip 400 defining anarray of wells filled with content and a membrane 402 sealed on chip 400over the array of wells, such that the surface of membrane 402 that wasin contact with chip 400, when peeled off chip 400, has impressions ofeach of the wells with samples of the well contents attached (e.g.,stuck) thereto, as shown in FIG. 4B. FIG. 4C is an image of a membranesurface with impressions formed from contact with an array of wells inaccordance with some embodiments.

A membrane may be impermeable, semi-permeable, selectively permeable,differentially permeable, and/or partially permeable to allow diffusionof at least one nutrient into the at least one microwell of a highdensity array of microwells. For example, a membrane may include anatural material and/or a synthetic material. A membrane may include ahydrogel layer and/or filter paper. In some embodiments, a membrane isselected with a pore size small enough to retain at least some or all ofthe cells in a microwell. For mammalian cells, the pore size may be afew microns and still retain the cells. However, in some embodiments,the pore size may be less than or equal to about 0.2 μm, such as 0.1 μm.Membrane diameters and pore sizes depend on the material. For example, ahydrophilic polycarbonate membrane may be utilized, for which thediameter may range from about 10 mm to about 3000 mm, and the pore sizemay range from about 0.01 μm to about 30.0 μm. An impermeable membranehas a pore size approaching zero. In embodiments with an impermeablemembrane, any nutrients must be provided in a microwell prior to beingsealed with the membrane. A membrane that is gas permeable but notliquid permeable may allow oxygen into a microwell and carbon dioxideout of the microwell. The membrane may have a complex structure that mayor may not have defined pore sizes. However, the pores may be on ananometer scale. Other factors in selecting a membrane may include cost,ability to seal, and/or ability to sterilize.

A substrate may define an array of microchannels extended from a firstsurface to a second surface opposite the first surface. A microchannelmay have a first opening in the first surface and a second opening inthe second surface. A first membrane may be applied to at least aportion of the first surface such that at least some of the populationof cells in at least one microchannel attach to the first membrane. Asecond detachable membrane may be applied to at least a portion of thesecond surface such that at least some of the population of cells in atleast one microchannel attach to the second membrane. The population ofcells in the at least one microchannel is sampled by peeling back thefirst membrane such that the at least some of the population of cells inthe at least one microchannel remain attached to the first membraneand/or the second membrane such that the at least some of the populationof cells in the at least one microchannel remain attached to the secondmembrane.

The term “high throughput” may refer to a capability of a system ormethod to enable quick performance of a very large number of experimentsin parallel or in series. An example of a “high throughput” system mayinclude automation equipment with cell biology techniques to prepare,incubate, and/or conduct a large number of chemical, genetic,pharmacological, optical, and/or imaging analyses to screen one or morebiological entities for at least one of a metabolite, an enzyme, aprotein, a nucleic acid, a phenotype, a mutation, a metabolic pathway, agene, an adaptation, and a capability, as discussed herein. According tosome embodiments, “high throughput” may refer to simultaneous or nearsimultaneous experiments on a scale ranging from at least about 96experiments to at least about 10,000,000 experiments.

Systems, kits, apparatus, and methods disclosed herein may be used forhigh throughput screening of different conditions against a matrix ofbiological entities (e.g., cells). A “wells-within-wells” concept may beimplemented by manufacturing (e.g., microfabricating) a substrate orchip to have multiple levels of functional layers to whatever level isrequired or desired (i.e., wells within wells within wells within wells,etc.). A first functional layer may define an array of experimentalunits (e.g., wells). Each of the experimental units presents a secondfunctional layer by defining a subsequent array of experimental units(e.g., microwells). This enables multiple experiments or tests to beperformed at the same time on a single chip, thus enabling highthroughput operation.

For example, in FIGS. 3A and 3B, gasket 306 is placed on top of membrane304, which is applied to an array of wells 302 on a microfabricateddevice 300 in accordance with some embodiments. Gasket 306 has only oneopening. However, in further embodiments, multiple smaller gaskets witha smaller opening or a single gasket with more than one smaller openingmay be placed on top of a device (either with or without a membrane),thereby forming a functional layer or an array of larger experimentalunits with a subsequent functional layer or subsequent array ofexperimental units (e.g., wells 302) located therein.

With multiple levels of functional layers, more than one nutrient ornutrient formulation, for example, can be tested simultaneously or nearsimultaneously. The same format may be used, for example, to screen formetabolites or specific capabilities of cells or to wean microorganismsfrom environmentally derived nutrients to other nutrients.

Experimental units are predetermined sites on a surface of amicrofabricated device. For example, a surface of a chip may be designedto immobilize cells in a first array of predetermined sites. Thesepredetermined sites may be wells, microwells, microchannels, and/ordesignated immobilization sites. For example, a surface may bemanufactured to define an array of microwells. The array may be dividedinto sections by defining walls in the substrate or adding walls. Forexample, the surface may be manufactured to first define a first arrayof wells, in which an inner surface of each well, in turn, ismanufactured to define a second array of microwells, microchannels, orimmobilization sites. In another example, the surface may bemanufactured to define an array of microwells, and another substrate(e.g., agar, plastic, or another material) is applied to the surface topartition the surface and the microwells defined thereby. Each well,microwell, microchannel, and/or immobilization site may be configured toreceive and grow at least one cell; however, in use, any given well,microwell, microchannel, or immobilization site may or may not actuallyreceive and/or grow one or more cells. Types of experimental units maybe interchangeable. For example, embodiments herein that expresslydescribe microwells are also intended to disclose embodiments in whichthe microwells are at least in part replaced with microchannels,immobilization sites, and/or other types of experimental units.

One or more portions of a microfabricated device may be selected,treated, and/or coated with a surface chemistry modifier to have aparticular surface chemistry. For example, at least a portion of asubstrate surface may be configured with first surface characteristicsthat repel cells and/or reduce cellular tendency to stick to the surfaceor second surface characteristics that attract cells and/or increasecellular tendency to attach to the surface. Depending on the type oftarget cell, the material and/or coating may be hydrophobic and/orhydrophilic. At least a portion of the top surface of the substrate maybe treated to have first surface characteristics that repel target cellsand/or reduce the tendency of target cells to stick to the surface.Meanwhile, at least a portion of the inner surface of each experimentalunit, well, or microwell may be treated to have second surfacecharacteristics that attract target cells and increase the tendency oftarget cells to occupy the experimental unit, well, or microwell. Asurface of a substrate may have a plurality of portions with differentsurface characteristics.

A surface chemistry modifier may be applied using chemical vapordeposition, electroporation, plasma treatment, and/or electrochemicaldeposition. The surface chemistry modifier may control surfacepotential, Lund potential, zeta potential, surface morphology,hydrophobicity, and/or hydrophilicity. The surface chemistry modifiermay include a silane, a polyelectrolyte, a metal, a polymer, anantibody, and/or a plasma. For example, the surface chemistry modifiermay include octadecyltrichlorosilane. The surface chemistry modifier mayinclude a dynamic copolymer, such as polyoxyethylene (20) sorbitanmonolaurate and/or polyethylene glycolp-(1,1,3,3-tetramethylbutyl)-phenyl ether. The surface chemistrymodifier may include a static copolymer, such as poloxamer 407,poly(L-lysine), and/or a poly(ethylene glycol)-poly(l-lysine) blockcopolymer.

An apparatus for screening different conditions against a matrix ofcells may include a substrate with a surface defining an array ofmicrowells. Sections of the microwell array may be partitioned intosubarrays (e.g., by larger wells or walls). The substrate may bemicrofabricated. Each microwell may receive and grow at least onebiological entity (e.g., cell). The resulting matrix of biologicalentities (e.g., cells) may be a high density matrix of biologicalentities. The first array and/or the second array may be planar,substantially planar, and/or multi-planar (e.g., on a roll).

The term “high resolution” may refer to a capability of a system ormethod to distinguish between a number of available experiments. Forexample, a “high resolution” system or method may select an experimentalunit from a microfabricated device comprising a high density ofexperimental units, in which the experimental unit has a diameter fromabout 1 nm to about 800 μm. A substrate of a microfabricated device orchip may include about or more than 10,000,000 microwells. For example,an array of microwells may include at least 96 locations, at least 1,000locations, at least 5,000 locations, at least 10,000 locations, at least50,000 locations, at least 100,000 locations, at least 500,000locations, at least 1,000,000 locations, at least 5,000,000 locations,or at least 10,000,000 locations.

The surface density of microwells may be from about 150 microwells percm2 to about 160,000 microwells per cm2 or more. A substrate of amicrofabricated device or chip may have a surface density of microwellsof at least 150 microwells per cm2, at least 250 microwells per cm2, atleast 400 microwells per cm2, at least 500 microwells per cm2, at least750 microwells per cm2, at least 1,000 microwells per cm2, at least2,500 microwells per cm2, at least 5,000 microwells per cm2, at least7,500 microwells per cm2, at least 10,000 microwells per cm2, at least50,000 microwells per cm2, at least 100,000 microwells per cm2, or atleast 160,000 microwells per cm2.

The dimensions of a microwell may range from nanoscopic (e.g., adiameter from about 1 to about 100 nanometers) to microscopic or larger.For example, each microwell may have a diameter of about 1 μm to about800 μm, a diameter of about 25 μm to about 500 μm, or a diameter ofabout 30 μm to about 100 μm. A microwell may have a diameter of about orless than 1 μm, about or less than 5 μm, about or less than 10 μm, aboutor less than 25 μm, about or less than 50 μm, about or less than 100 μm,about or less than 200 μm, about or less than 300 μm, about or less than400 μm, about or less than 500 μm, about or less than 600 μm, about orless than 700 μm, or about or less than 800 μm.

A microwell may have a depth of about 500 μm to about 5000 μm, a depthof about 1 μm to about 500 μm, or a depth of about 25 μm to about 100μm. A microwell may have a depth of about 1 μm, about 5 μm, about 10 μm,about 25 μm, about 50 μm, about 100 μm, about 200 μm, about 300 μm,about 400 μm, about 500 μm, about 600 μm, about 700 μm, about 800 μm,about 1000 μm, about 1,500 μm, about 2,000 μm, about 3,000 μm, or about5,000 μm.

Each microwell may have an opening or cross section having any shape,e.g., round, hexagonal, or square. For microwells that are not round intheir openings or cross sections, the diameter of the microwellsdescribed herein refer to the effective diameter of a circular shapehaving an equivalent area. For example, for a square shaped microwellhaving side lengths of 10×10 microns, a circle having an equivalent area(100 square microns) has a diameter of 11.3 microns. Each microwell mayinclude sidewalls. The sidewalls may have a cross-sectional profile thatis straight, oblique, and/or curved. At least one uniquelocation-specific tag, as described further below, may be disposed in atleast one microwell of the high density array of microwells tofacilitate identification of a species and a correlation of a species toa specific microwell of the high density array of microwells. The atleast one unique tag may be disposed and/or positioned at the bottom ofthe microwell and/or on at least one side of the microwell. The at leastone unique tag may include a nucleic acid molecule with atarget-specific nucleotide sequence for annealing to a target nucleicacid fragment of the at least one biological entity and alocation-specific nucleotide sequence for identifying the at least onemicrowell of the high density array of microwells.

For example, a substrate of a microfabricated device or chip may have asurface with dimensions of about 4 inches by 4 inches. The surface maydefine an array of approximately 100 million microwells. The microwellarray may be partitioned into about 100 subsections by walls and/or thesubstrate may define an array of about 100 wells, with about one millionmicrowells defined within each subsection or well totaling toapproximately 100 million microwells. For a use case of testingdifferent nutrients, microorganisms from an environmental sample may beloaded on the chip such that individual microorganisms or clusters ofmicroorganisms partition into the microwells on the chip, each microwellbeing located at the bottom of a larger well. Each larger well mayinclude an experimental unit such that about 100 different nutrients maybe tested in parallel or in series on the same chip, with each wellproviding up to 1 million test cases.

Target cells may be Archaea, Bacteria, or Eukaryota (e.g., fungi,plants, or animals). For example, target cells may be microorganisms,such as aerobic, anaerobic, and/or facultative aerobic microorganisms.Different nutrients may be tested in parallel or in series on acomposition of target cells to analyze and compare, for instance, growthor other effects on cell population, cell components, and/or cellproducts. A composition of target cells may be screened for a cellcomponent, product, and/or capability, such as one or more of a virus(e.g., a bacteriophage), a cell surface (e.g., a cell membrane or wall),a metabolite, a vitamin, a hormone, a neurotransmitter, an antibody, anamino acid, an enzyme, a protein, a saccharide, ATP, a lipid, anucleoside, a nucleotide, a nucleic acid (e.g., DNA or RNA), aphenotype, a mutation, a metabolic pathway, a gene, and an adaptation.

A composition of cells may include an environmental sample extractand/or a dilutant. The environmental sample extract and/or the dilutantmay include, but is not limited to, one or more of a biological tissue(e.g., connective, muscle, nervous, epithelial, plant epidermis,vascular, ground, etc.), a biological fluid or other biological product(e.g., amniotic fluid, bile, blood, cerebrospinal fluid, cerumen,exudate, fecal matter, gastric fluid, interstitial fluid, intracellularfluid, lymphatic fluid, milk, mucus, rumen content, saliva, sebum,semen, sweat, urine, vaginal secretion, vomit, etc.), a microbialsuspension, air (including, e.g., different gas contents), supercriticalcarbon dioxide, soil (including, e.g., minerals, organic matter, gases,liquids, organisms, etc.), sediment (e.g., agricultural, marine, etc.),living organic matter (e.g., plants, insects, other small organisms andmicroorganisms), dead organic matter, forage (e.g., grasses, legumes,silage, crop residue, etc.), a mineral, oil or oil products (e.g.,animal, vegetable, petrochemical), alcohol, a buffer, an organicsolvent, water (e.g., naturally-sourced freshwater, drinking water,seawater, etc.), and/or sewage (e.g., sanitary, commercial, industrial,and/or agricultural wastewater and surface runoff).

A method may include, prior to applying (e.g., loading) a compositionincluding cells to a microfabricated device, preparing the compositionby combining the cells with an environmental sample extract and/or adilutant. The method further may include liquefying the environmentalsample extract and/or the dilutant. A concentration of cells in acomposition may be adjusted to target distribution of one cell perexperimental unit, well, or microwell.

If a sample contains cells and/or viruses, the cells in the sample maybe lysed after they are applied to a microfabricated device to releasenucleic acid molecules. Cells may be lysed with chemical treatment suchas alkaline exposure, detergents, sonication, enzymatic proteinase K, orlysozyme exposure. Cells may also be lysed by heating.

FIG. 5A is a flowchart illustrating a method for isolating cells from asample in accordance with some embodiments. In step 500, a sample isobtained. In step 502, the sample is homogenized and/or dispersed usingat least one of a physical technique (e.g., blending and/or sonication)and a chemical technique (e.g., chelating agents, detergents, and/orenzymes). In step 504, cells in the homogenized and/or dispersed sampleare separated by density centrifugation using, for example, Nycodenz®non-particulate medium (available from Progen Biotechnik GmbH,Heidelberg, Germany).

FIG. 5B is a diagram illustrating a method for isolating cells from asoil sample in accordance with some embodiments. Panel 506 shows thesoil sample. Panel 508 shows the homogenized and/or dispersed sample ina test tube. Panel 510 shows the sample after centrifugation, separatedinto soluble debris 512, cells 514, insoluble debris 516, and Nycodenz®518.

FIG. 6 is a flowchart illustrating a method for isolating andcultivating cells from a sample in accordance with some embodiments. Instep 600, a sample is obtained. In step 602, at least one cell isextracted from the obtained sample. In step 604, at least one highdensity microwell array of a microfabricated device or chip is loadedwith the at least one extracted cell. Step 604 may include preparing acell concentration with the at least one extracted cell, selecting atleast one nutrient/media, and/or selecting at least one membrane. Instep 606, at least a portion of the microwell array is sealed with theat least one selected membrane to retain the cell concentration with themicrowells. In step 608, the chip is incubated. Step 608 may includeselecting a temperature, determining atmosphere (e.g., aerobic oranaerobic), and/or timing incubation). In step 610, the chip is splitand/or substantially replicated (using, e.g., a picker), resulting intwo portions of cultivated cells according to methods described herein.For example, the at least one membrane may be peeled off such that aportion of the cultivated cells remain attached or peeled off orpunctured to sample the cultivated cells. In optional step 612, oneportion of the cultivated cells is sacrificed for identification. Step612 may include PCR, sequencing, and/or various data analytics. In step614, strains of interest are identified. Further cultivation, testing,and/or identification may be performed with, for example, the strains ofinterest and/or the remaining portion of the cultivated cells.

FIG. 7 is a diagram illustrating a method for isolating and cultivatingcells from a complex sample in accordance with some embodiments. Panel700 shows examples of complex samples, specifically a microbiome sample702 and a soil sample 704. In Panel 706, at least one cell is extractedfrom the sample using, for example, the protocol illustrated in FIGS. 5Aand 5B. In Panel 708, the at least one extracted cell (and anyenvironmental extract and/or dilutant) is loaded on a microfabricateddevice or chip with at least one high density microwell array 710. Chip710 and a reagent cartridge 712 may be loaded into an incubator 714. Thereagent may be useful for adding liquid to maintain nutritionalrequirements for growth and/or various screening purposes. Panel 716shows the output: isolated strains of cultivated cells.

To identify the species or taxonomic lineage of cells or microorganismsgrowing in a microwell requires techniques including, but not limitedto, DNA sequencing, nucleic acid hybridization, mass spectrometry,infrared spectrometry, DNA amplification, and antibody binding toidentify genetic elements or other species identifiers. Manyidentification methods and process steps kill the microorganisms andtherefore prevent further cultivation and study of microorganisms ofinterest. To enable both the identification of cells or microorganismswhile enabling subsequent cultivation, study, and further elaboration ofparticular clones of interest, further embodiments are designed forsampling each experimental unit, well, or microwell across a substrateor chip while maintaining the locational integrity and separation ofmicroorganism populations across experimental units, wells, ormicrowells.

A substrate as described above may enable sampling a cell populationusing further systems, kits, apparatus, and methods. For example, apicking device may be applied to a first surface of the substrate. Thedevice may include at least one protrusion facing the first surface. Theat least one protrusion has a diameter less than the opening diameter ofeach microwell, well, or experimental unit. The at least one protrusionmay be inserted into at least one microwell, well, or experimental unitholding a population of cells such that a portion of the population ofcells in the at least one microwell, well, or experimental unit adheresand/or attaches to the at least one protrusion. The sample of thepopulation of cells in the at least one microwell, well, or experimentalunit may be withdrawn by removing the device from the first surface ofthe substrate such that the portion of the population of cells in the atleast one microwell, well, or experimental unit remains adhered and/orattached to the at least one protrusion. Each protrusion may be a pin ora plurality or assembly of pins.

FIGS. 8A-8C are diagrams illustrating picking by one pin or multiplepins in accordance with some embodiments. Chip 800 is provided forinspection via a microscope 802 and picking via picking control device804. In FIG. 8A, picking control device 804 comprises an arm with asingle pin 806. In FIG. 8B, an arm with multiple pins 808 is shown. FIG.8C is a perspective view of the chip during the picking process.

FIGS. 9A-9D are images demonstrating picking of a well in accordancewith some embodiments. In FIG. 9A, the well is full. In FIG. 9B, the pinis moved into position. In FIG. 9C, the well is picked. In FIG. 9D, asample is removed from the well.

FIGS. 10A-10D are diagrams illustrating a tool for picking a chip inaccordance with some embodiments. In FIG. 10A, a tool comprising aplurality of pins is aligned with a chip having a plurality of wells. InFIG. 10B, the tool is lowered such that the pins are dipped into thewells. In FIG. 10C, the pins are shown with samples attached, and thesamples are transferred to a new chip. Alternatively, in FIG. 10D, thetool is flipped such that the samples may be maintained in the toolitself.

FIG. 11 is an image of a well that has been picked through a thin layerof agar, illustrating picking through a membrane or sealing layer inaccordance with some embodiments.

Alternatively, when the at least one protrusion is inserted into the atleast one microwell, well, or experimental unit, a portion of thepopulation of cells in the at least one the at least one microwell,well, or experimental unit is volume displaced up and around the atleast one protrusion such that at least some of the volume displacedportion is above the first surface of the substrate and/or the innersurface of the at least one microwell, well, or experimental unit. Themethod also includes sampling the population of cells in the at leastone microwell by collecting at least some of the volume displacedportion of the population of cells.

A similar picking device may be applied to a second surface opposite thefirst surface of the substrate. The device may include at least oneprotrusion facing the second surface. The at least one protrusion has adiameter about equal to or less than a diameter of at least onemicrowell, well, or experimental unit. The at least one protrusion ispushed against the second surface at a location corresponding to the atleast one microwell, well, or experimental unit holding a population ofcells and/or inserted into the at least one microwell, well, orexperimental unit holding the population of cells such that a portion ofthe population of cells in the at least one microwell, well, orexperimental unit is displaced above the first surface of the substrateand/or the inner surface of the at least one microwell, well, orexperimental unit. The displaced portion of the population of cells maythen be collected. The population of cells may be located on a plug(e.g., a hydrogel or other soft material like agar) in the at least oneexperimental unit, well, or microwell such that when the at least oneprotrusion is at least one of pushed against the second surface andinserted into the at least one microwell, the plug is displaced, therebydisplacing the portion of the population of cells.

The sample of the population of cells from the at least one experimentalunit, well, or microwell may be deposited in a second location. The atleast one protrusion may be cleaned and/or sterilized prior to furthersampling. At least a portion of the at least one protrusion may becomposed of a material, treated, and/or coated with a surface chemistrymodifier for surface characteristics that favor attachment of cells. Theat least one protrusion may be an array of protrusions. Upon applyingthe device to the first surface of the substrate, the array ofprotrusions may be inserted into a corresponding array of experimentalunits, wells, or microwells. The number of protrusions in the array ofprotrusions may correspond to the number of experimental units in thefirst array, the number of microwells in one second array of microwells,or the total number of microwells in the substrate.

Another device for sampling a cell population in a substrate includes atleast one needle and/or nanopipette facing the first surface. The atleast one needle and/or nanopipette has an external diameter less thanthe opening diameter of each microwell and an internal diameter capableof accommodating a target cell diameter. The at least one needle and/ornanopipette is inserted into at least one experimental unit, well, ormicrowell holding a population of cells. The sample of the population ofcells in the at least one experimental unit, well, or microwell iswithdrawn using pressure to pull a portion of the population of cellsfrom the at least one experimental unit, well, or microwell into thedevice.

The sample of the population of cells from the at least one experimentalunit, well, or microwell may be deposited in a second location. The atleast one needle and/or nanopipette may be cleaned and/or sterilizedprior to further sampling. The at least one needle and/or nanopipettemay be an array of needles and/or nanopipettes. Upon applying the deviceto the first surface of the microfabricated substrate, the array ofneedles and/or nanopipettes may be inserted into a corresponding arrayof experimental units, wells, or microwells. The number of needlesand/or nanopipettes in the array of needles and/or nanopipettes maycorrespond to the number of the experimental units in the first array,the number of microwells in one second array of microwells, or the totalnumber of microwells in the substrate.

Another method for sampling a cell population in a substrate includesapplying focused acoustic energy to at least one experimental unit,well, or microwell holding a population of cells in fluid. The focusedacoustic energy may be applied in a manner effective to eject a dropletfrom the at least one microwell, such as, for example, acoustic dropletejection (ADE) (see, e.g., Sackmann et al., “Acoustical Micro- andNanofluidics: Synthesis, Assembly and Other Applications,” Proceedingsof the 4th European Conference on Microfluidics (December 2014)). Thedroplet may include a sample of the population of cells in the at leastone experimental unit, well, or microwell. The droplet may be directedinto a second container or surface or substrate.

A substrate may include at least a first piece including at least aportion of the first surface and a second piece including at least aportion of the second surface. The first piece and the second piece aredetachably connected along at least a portion of a plane parallel to thefirst surface and the second surface. The plane divides the experimentalunits, wells, or microwells. A cell population in at least oneexperimental unit, well, or microwell is sampled by detaching the firstpiece and the second piece such that a first portion of the populationof cells in the at least one experimental unit, well, or microwellremains attached to the first piece and a second portion of thepopulation of cells in the at least one experimental unit, well, ormicrowell remains attached to the second piece.

FIG. 12 is a diagram illustrating a cross-section of a chip 1200 inaccordance with some embodiments. Chip 1200 includes a substratedefining an array of wells 1202 filled with contents 1204. The substratecomprises a first piece 1206 and a second piece 1208. The first piece1206 and the second piece 1208 are detachably connected along a plane1210 parallel to and bisecting the array of wells 1202. When the firstpiece 1206 and the second piece 1208 are detached, the wells 1202 andtheir contents 1204 are divided, resulting in two copies of the contents1204 that preserve both the isolation and the location of the contents1204 on chip 1200.

Each microwell, experimental unit, or microchannel may include a partialbarrier that partially separates the microwell, experimental unit, ormicrochannel into a first portion and a bottom portion such that a cellpopulation is able to grow in both the first portion and the bottomportion. Prior to sampling the population of cells, the above methodsmay include dispersing and/or reducing clumps of cells in the populationof cells. Dispersing and/or reducing clumps of cells in the populationof cells may include, but is not limited to, applying sonication,shaking, and dispension with small particles.

The above methods further may include depositing the sample of thepopulation of cells from the at least one experimental unit, well, ormicrowell in a second location. The second location may be acorresponding array of experimental units, wells, or microwells. Thesecond location may be a single receptacle. The sample of the populationof cells from the at least one experimental unit, well, or microwell maybe maintained for subsequent cultivation. Alternatively, the remainingcells of the population of cells in the at least one experimental unit,well, or microwell may be maintained for subsequent cultivation.

The above methods further may include identifying at least one cell fromthe sample of the population of cells and/or the remaining cells of thepopulation of cells. This may include performing DNA, cDNA, and/or RNAamplification, DNA and/or RNA sequencing, nucleic acid hybridization,mass spectrometry, and/or antibody binding. Alternatively, or inaddition, this may include identifying an experimental unit, well, ormicrowell from which at least one cell originated. Each experimentalunit, well, or microwell may be marked with a unique tag including alocation-specific nucleotide sequence. To identify the experimentalunit, well, or microwell, a location-specific nucleotide sequence may beidentified in the sequencing and/or amplification reaction, and thelocation specific nucleotide sequence may be correlated with the atleast one experimental unit, well, or microwell from which the at leastone cell originated.

A microfabricated device as described above may enable culturing cellsin a sample derived from an environment using further systems, kits,apparatus, and methods. For example, a sample may be applied to thefirst surface of a substrate such that at least one of the cellsoccupies at least one microwell, well, or experimental unit. Asemi-permeable membrane is applied to at least a portion of the firstsurface (e.g., at least a portion of an inner surface of an experimentalunit or well) such that a nutrient can diffuse into the at least onemicrowell, well, or experimental unit. Meanwhile, escape of theoccupying cells from the at least one microwell, well, or experimentalunit is prevented and/or mitigated. A semi-permeable membrane may be,for example, a hydrogel layer. A semi-permeable membrane may bereversibly or irreversibly connected or affixed to the substrate using,for example, lamination. Thus, the occupying cells may be incubated inthe at least one microwell, well, or experimental unit with at least onenutrient. The cells may be gradually transitioned over a period of timefrom at least one nutrient to at least one alternative nutrient ornutrient formulation using progressive partial exchange, therebyundergoing domestication or adaptation.

A first nutrient derived from the environment may be used to incubatethe cells occupying at least one first experimental unit, well, ormicrowell, and a second nutrient derived from the environment may beused to incubate the cells occupying at least one second experimentalunit, well, or microwell. The above methods may include comparing thecells occupying the at least one first experimental unit, well, ormicrowell with the cells occupying at least one second experimentalunit, well, or microwell to analyze the first nutrient and the secondnutrient.

For example, a method may include one or more of the following steps:

-   -   Acquire a chip defining 1000 to 10 million or more microwells        within a number of larger wells or flow cells, each microwell        having a diameter of about 1 μm to about 800 μm and a depth of        about 1 μm to about 800 μm, the chip further having one or more        surface chemistries configured to facilitate the movement of        target microorganisms into the microwells;    -   Apply an environmental sample or a derivative of the        environmental sample to the chip such that any target        microorganisms become located in the microwells;    -   Place one or more semi-permeable filters, hydrogel layers, or        other barriers on the chip such that a barrier is created that        allows nutrients to diffuse into the microwells but prevents        and/or mitigates escape of microorganisms from the microwells;    -   Incubate the chip with at least one nutrient (e.g., derived from        the environment);    -   Gradually change the nutrient source by progressive partial        exchange with at least one alternative nutrient (e.g.,        formulation); and    -   Detect any growth of microorganisms in the microwells.

The target cells may be Archaea, Bacteria, or Eukaryota. Target virusesmay be bacteriophages. When viruses are targeted, the microwells of thechip may also include host cells in which the viruses may grow.Detecting the growth of the occupying cells or viruses may includedetecting a change in biomass (e.g., DNA/RNA/protein/lipid), metabolitepresence or absence, pH, consumption of nutrients, and/or consumption ofgases. Detecting the growth of the occupying cells or viruses mayinclude performing real-time sequential imaging, microscopy, opticaldensity, fluorescence microscopy, mass spectrometry, electrochemistry,amplification (DNA, cDNA, and/or RNA), sequencing (DNA and/or RNA),nucleic acid hybridization, and/or antibody binding.

FIG. 13 is a flowchart illustrating methods for screening in accordancewith some embodiments. In step 1300, a sample is obtained. In step 1302,at least one cell is extracted from the obtained sample. In step 1304,at least one high density microwell array of a microfabricated device orchip is loaded with the at least one extracted cell. Step 1304 mayinclude preparing a cell concentration with the at least one extractedcell, selecting at least one nutrient/media, and/or selecting at leastone membrane. In step 1306, at least a portion of the microwell array issealed with the at least one selected membrane to retain the cellconcentration with the microwells. In step 1308, the chip is incubated.Step 1308 may include selecting a temperature, determining atmosphere(e.g., aerobic or anaerobic), and/or timing incubation). A geneticscreen and/or a functional screen may be performed. In step 1310, agenetic screen is applied to the chip. In step 1312, the chip is splitand/or substantially replicated (using, e.g., a picker), resulting intwo portions of cultivated cells according to methods described herein.For example, the at least one membrane may be peeled off such that aportion of the cultivated cells remain attached or peeled off orpunctured to sample the cultivated cells. In optional step 1314, oneportion of the cultivated cells is sacrificed for identification. Step1314 may include PCR, sequencing, and/or various data analytics. In step1316, strains of interest are identified. Further cultivation, testing,and/or identification may be performed with, for example, the strains ofinterest and/or the remaining portion of the cultivated cells.Alternatively, in step 1318, a functional screen is applied to the chip.In step 1320, one or more variables are observed and, as in step 1316,strains of interest are identified.

FIG. 14 is a diagram illustrating a screening method in accordance withsome embodiments. Panel 1400 shows examples of complex samples,specifically a microbiome sample 1402 and a soil sample 1404. In Panel1406, at least one cell is extracted from the sample using, for example,the protocol illustrated in FIGS. 5A and 5B. In Panel 1408, the at leastone extracted cell (and any environmental extract and/or dilutant) isloaded on a microfabricated device or chip with at least one highdensity microwell array 1410. Chip 1410 and a reagent cartridge 1412 maybe loaded into an incubator 1414. The reagent may be useful for addingliquid to maintain nutritional requirements for growth and/or variousscreening purposes. Panel 1416 shows the output: screen results andisolated strains of cultivated cells.

FIG. 15 is a series of images illustrating a screening example inaccordance with some embodiments. The images show portions of a chipwith a membrane and an acid-sensitive layer applied thereon to screenfor low pH. In image 1500, more than 1800, 50-μm microwells are visiblewith nine clear hits 1502. Image 1504 is a magnified view of box 1504,and image 1506 is a magnified view of one of the microwells with a hit1502.

FIGS. 16A-16C are images illustrating recovery from a screen inaccordance with some embodiments. In FIG. 16A, at least one well ispicked using a microscope and a picking device with at least one pin. InFIG. 16B, a pin is removed and incubated in media. In FIG. 16C, growthis visible.

FIG. 17A is an exploded diagram illustrating a chip for screening inaccordance with some embodiments. In FIG. 17A, chip 1700 includes a highdensity array of microwells with, for example, soil microbes in themicrowells. Membrane 1702 is applied to chip 1700. Gasket 1704 isapplied to chip 1700 over membrane 1702. Agar with fluorescent E. colibacteria 1706 is applied to chip 1700 over gasket 1704 and membrane1702. FIGS. 17B and 17C are images illustrating a screening example inaccordance with some embodiments. In this example, the screen is forclearance zones. FIG. 17B is a fluorescence image of a chip, preparedlike chip 1700 in FIG. 17A, following the screen. FIG. 17C is an imageshowing a process of picking a sample from this chip through the agar.

In some embodiments, a location on an apparatus may be correlated with aportion of a sample present at that location, after that portion of thesample (or a part of the portion) is removed from the apparatus. Theapparatus may be or include a microarray. The microarray may comprise aplurality of locations for applying a sample, wherein each location ismarked with a unique tag which may be used to identify the location fromwhich a portion of the sample came, after that portion of the sample isremoved from the microarray.

The disclosure relates to a method of identifying from which location ona microarray a portion of a sample comprising at least one nucleic acidmolecule came, after that portion of the sample is removed from themicroarray, the method comprising the steps of: (a) applying one or moreportions of the sample onto one or more of a plurality of locations onthe microarray, wherein each location is marked with a unique tagcomprising a nucleic acid molecule comprising: (i) a location-specificnucleotide sequence; and (ii) a first target-specific nucleotidesequence; (b) allowing the target nucleic acid molecule found in atleast one portion of the sample to anneal to a tag marking a location;(c) performing primer extension, reverse transcription, single-strandedligation, or double-stranded ligation on the population of annealednucleic acid molecules, thereby incorporating a location-specificnucleotide sequence into each nucleic acid molecule produced by primerextension, reverse transcription, single-stranded ligation, ordouble-stranded ligation; (d) combining the population of nucleic acidmolecules produced in step (c); (e) sequencing the population ofcombined nucleic acid molecules, thereby obtaining the sequence of oneor more location-specific nucleotide sequences; and (f) correlating thesequence of at least one location-specific nucleotide sequence obtainedfrom the population of combined nucleic acid molecules to the locationon the microarray marked with a tag comprising said location-specificnucleotide sequence; thereby identifying from which location on amicroarray a portion of a sample comprising at least one nucleic acidmolecule came. In some embodiments, a sample may include at least onecell and one or more nucleic acid molecules are released from the cellafter step (a) and before step (b). A sample may include at least onecell, and the at least one cell replicates or divides after step (a) andbefore step (b). A portion of the portion of the sample may be removedfrom at least one location before step (b) and said portion of theportion of the sample may be stored in a separate receptacle correlatedto the original location of the portion of the sample on the microarray.The method of correlating or identifying a location may further comprisethe step of amplifying the nucleic acid molecules produced in step (c)or the population of combined nucleic acid molecules produced in step(d). The amplifying step may comprise polymerase chain reactionamplification, multiplexed polymerase chain reaction amplification,nested polymerase chain reaction amplification, ligase chain reactionamplification, ligase detection reaction amplification, stranddisplacement amplification, transcription based amplification, nucleicacid sequence-based amplification, rolling circle amplification, orhyper-branched rolling circle amplification. Additional primers may beadded during an amplification reaction. For example, both 5′ and 3′primers may be needed for a PCR reaction. One of the primers used duringan amplification reaction may be complementary to a nucleotide sequencein the sample.

In some embodiments, a composition including cells and/or viruses may betreated with a nuclease before the composition is applied to amicrofabricated device so that contaminating nucleic acid molecules arenot amplified in subsequent steps.

The sequencing used in the disclosed methods and apparatuses may be anyprocess of obtaining sequence information, including hybridization anduse of sequence specific proteins (for example, enzymes). Sequencing maycomprise Sanger sequencing, sequencing by hybridization, sequencing byligation, quantitative incremental fluorescent nucleotide additionsequencing (QIFNAS), stepwise ligation and cleavage, fluorescenceresonance energy transfer, molecular beacons, TaqMan reporter probedigestion, pyrosequencing, fluorescent in situ sequencing (FISSEQ),wobble sequencing, multiplex sequencing, polymerized colony (POLONY)sequencing (see, e.g., U.S. Patent Application Publication No.2012/0270740, which is incorporated by reference herein in itsentirety); nanogrid rolling circle (ROLONY) sequencing (see, e.g., U.S.Patent Application Publication No. 2009/0018024, which is incorporatedby reference herein in its entirety), allele-specific oligo ligationassay sequencing, or sequencing on a next-generation sequencing (NGS)platform. Non-limiting examples of NGS platforms include systems fromIllumina® (San Diego, Calif.) (e.g., MiSeg™, NextSeg™ HiSeq™, and HiSeqX™), Life Technologies (Carlsbad, Calif.) (e.g., Ion Torrent™), andPacific Biosciences (Menlo Park, Calif.) (e.g., PacBio® RS II).

An organism or species may be identified by comparing the nucleic acidsequence obtained from that organism to various databases containingsequences of organisms. For example, ribosomal RNA sequence data isavailable in the SILVA rRNA database project (Max Planck Institute forMarine Microbiology, Bremen, Germany (www.arb-silva.de); see, e.g.,Quast et al., “The SILVA Ribosomal RNA Gene Database Project: ImprovedData Processing and Web-Based Tools,” 41 Nucl. Acids Res. D590-D596(2013), and Pruesse et al., “SINA: Accurate High-Throughput MultipleSequence Alignment of Ribosomal RNA Genes,” 28 Bioinformatics 1823-1829(2012), both of which are incorporated by reference herein in theirentirety). Other ribosomal RNA sequence databases include the RibosomalDatabase Project (Michigan State University, East Lansing, Mich.(www.rdp.cme.msu.edu); see, e.g., Cole et al., “Ribosomal DatabaseProject: Data and Tools for High Throughput rRNA Analysis” 42 Nucl.Acids Res. D633-D642 (2014), which is incorporated by reference hereinin its entirety) and Greengenes (Lawrence Berkeley National Laboratory,Berkeley, Calif. (www.greengenes.lbl.gov); see, e.g., DeSantis et al.,“Greengenes, a Chimera-Checked 16S rRNA Gene Database and WorkbenchCompatible with ARB,” 72 Appl. Environ. Microbiol. 5069-72 (2006), whichis incorporated by reference herein in its entirety). The GenBank®genetic sequence database contains publicly available nucleotidesequences for almost 260,000 formally described species (NationalInstitutes of Health, Bethesda, Md. (www.ncbi.nlm.nih.gov); see, e.g.,Benson et al., “GenBank,” 41 Nucl. Acids Res. D36-42 (2013).

The sequence used for matching and identification may include the 16Sribosomal region, 18S ribosomal region or any other region that providesidentification information. The desired variant may be a genotype (e.g.,single nucleotide polymorphism (SNP) or other type of variant) or aspecies containing a specific gene sequence (e.g., a sequence coding foran enzyme or protein). An organism or species may also be identified bymatching its sequence to a custom internal sequence database. In somecases, one may conclude that a certain species or organism is found at alocation on the microarray if the sequence obtained from the portion ofthe sample at the location has at least a specified percentage identity(e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least94%, at least 95%, at least 96%, at least 97%, at least 98%, at least99%, or 100% identity) to the known DNA, cDNA, or RNA sequence obtainedfrom that species or microorganism.

The disclosure further relates to a method of manufacturing a microarraycomprising a plurality of locations for applying a sample, wherein atleast one location is marked with a unique tag, the method comprisingthe steps of: (a) synthesizing a plurality of tags, wherein each tagcomprises a nucleic acid molecule comprising: (i) a location-specificnucleotide sequence; and (ii) a target-specific nucleotide sequence; and(b) placing a tag on at least one location of the plurality of locationson the microarray. In an alternative embodiment, the disclosure relatesto a method of manufacturing a microarray comprising a plurality oflocations for applying a sample, wherein at least one location is markedwith a unique tag, the method comprising the steps of: (a) synthesizinga plurality of tags, wherein each tag comprises a nucleic acid moleculecomprising: a target-specific nucleotide sequence and not comprising alocation-specific nucleotide sequence; and (b) placing a tag on at leastone location of the plurality of locations on the microarray. Thetarget-specific sequence may be the same at every location in themicroarray. In either of the above embodiments, step (a) may beperformed before step (b). The placing step (b) may comprise placing thetag at each location by a liquid handling procedure (for example,pipetting, spotting with a solid pin, spotting with a hollow pin, ordepositing with an inkjet device). At least one tag may include anucleic acid molecule or a portion of a nucleic acid molecule that ispre-synthesized. Step (a) may be performed simultaneously with step (b).In certain embodiments, at least one tag comprises a nucleic acidmolecule that is synthesized at each location by in situ synthesis. Thesynthesizing step (a) may comprise inkjet printing synthesis orphotolithography synthesis.

Each location on a microarray may be configured to receive a portion ofthe sample. A location may be tagged or labeled with a nucleic acidmolecule (e.g., an oligonucleotide) that comprises at least one of: (i)a location-specific nucleotide sequence (e.g., a barcode); and (ii) atarget-specific nucleotide sequence. A target-specific nucleotidesequence may complement or substantially complement a nucleotidesequence found in the sample. The order of the nucleotide sequences fromthe 5′ end to the 3′ end in the nucleic acid molecule may be: (1) alocation-specific nucleotide sequence; and (2) a target-specificnucleotide sequence. Alternatively, the order of the nucleotidesequences from the 5′ end to the 3′ end in the nucleic acid molecule maybe (2) then (1). The nucleic acid molecule may be attached at its 5′ endto the microarray. One or more locations on the apparatus (e.g.,microarray) may be untagged or unlabeled.

The terms “complementary” or “substantially complementary” may refer tothe hybridization, the base pairing, or the formation of a duplexbetween nucleotides or nucleic acids, such as, for instance, between thetwo strands of a double stranded DNA molecule or between anoligonucleotide primer and a primer binding site on a single strandednucleic acid. Complementary nucleotides are, generally, A and T/U, or Cand G. Two single-stranded RNA or DNA molecules are said to besubstantially complementary when the nucleotides of one strand,optimally aligned and compared and with appropriate nucleotideinsertions or deletions, pair with at least about 80% of the nucleotidesof the other strand, usually at least about 90% to 95%, and morepreferably from about 98 to 100%. Alternatively, substantialcomplementarity exists when an RNA or DNA strand will hybridize underselective hybridization conditions to its complement. Typically,selective hybridization will occur when there is at least about 65%complementary over a stretch of at least 14 to 25 nucleotides, at leastabout 75%, or at least about 90% complementary.

The term “selectively hybridize” or “selective hybridization” may referto binding detectably and specifically. Polynucleotides,oligonucleotides and fragments thereof selectively hybridize to nucleicacid strands under hybridization and wash conditions that minimizeappreciable amounts of detectable binding to nonspecific nucleic acids.“High stringency” or “highly stringent” conditions can be used toachieve selective hybridization conditions as known in the art anddiscussed herein. An example of “high stringency” or “highly stringent”conditions is a method of incubating a polynucleotide with anotherpolynucleotide, wherein one polynucleotide may be affixed to a solidsurface such as a membrane, in a hybridization buffer of 6×SSPE or SSC,50% formamide, 5×Denhardt's reagent, 0.5% SDS, 100 μg/ml denatured,fragmented salmon sperm DNA at a hybridization temperature of 42° C. for12-16 hours, followed by twice washing at 55° C. using a wash buffer of1×SSC, 0.5% SDS.

The nucleic acid molecule that is part of a location tag may comprise atleast one deoxyribonucleotide or at least one ribonucleotide. Thenucleic acid molecule may be single-stranded or double-stranded. Anucleic acid molecule may be a double-stranded molecule having asingle-stranded overhang.

In some embodiments, the location tag may be used to amplify a nucleicacid molecule that anneals to it. Thus, the location tag may comprise anucleic acid sequence that further comprises an amplification primerbinding site. An amplification primer binding site may be at least 16,at least 17, at least 18, at least 19, at least 20, at least 21, atleast 22, at least 23, at least 24, at least 25, at least 26, at least27, at least 28, at least 29, or at least 30 nucleotides in length. Theorder of the nucleotide sequences from the 5′ end to the 3′ end in thenucleic acid molecule may be, for example: (1) the amplification primerbinding site; (2) the location-specific nucleotide sequence; and (3) thetarget-specific nucleotide sequence.

In some embodiments, a nucleic acid molecule may comprise atarget-specific nucleotide sequence without comprising alocation-specific nucleotide sequence. In certain embodiments, a nucleicacid molecule may comprise a target-specific nucleotide sequence withoutcomprising either a location-specific nucleotide sequence or anamplification binding site sequence. In further embodiments, a nucleicacid molecule may comprise only a target-specific nucleotide sequence.In even further embodiments, a nucleic acid molecule may contain only atarget-specific nucleotide sequence. The amplification primer bindingsite may be capable of binding to a polymerase chain reaction primer, amultiplexed polymerase chain reaction primer, a nested polymerase chainreaction primer, a ligase chain reaction primer, a ligase detectionreaction primer, a strand displacement primer, a transcription basedprimer, a nucleic acid sequence-based primer, a rolling circle primer,or a hyper-branched rolling circle primer. Additional primers may beadded to the microarray during an amplification reaction. For example,both 5′ and 3′ primers may be needed for a PCR reaction. Target-specificnucleotide sequences may be amplified in the locations containing targetnucleic acid molecules and may be detected by, for example, qPCR, endpoint PCR, and/or dyes to detect amplified nucleic acid molecules.

It may be desirable to sequence a nucleic acid molecule that anneals toa location tag or the amplified product based on such a nucleic acidmolecule. The location tag may comprise a nucleic acid sequence thatfurther comprises an adapter nucleotide sequence.

In certain embodiments, an adapter nucleotide sequence may not be foundin the location tag but is added to the sample nucleic acid molecules ina secondary PCR reaction or by ligation. An adapter nucleotide sequencemay be a generic adapter or an adapter for a specific sequencingplatform (e.g., Illumina® or Ion Torrent™). An adapter nucleotidesequence may include a sequencing primer binding site. A sequencingprimer binding site may be capable of binding a primer for Sangersequencing, sequencing by hybridization, sequencing by ligation,quantitative incremental fluorescent nucleotide addition sequencing(QIFNAS), stepwise ligation and cleavage, fluorescence resonance energytransfer, molecular beacons, TaqMan reporter probe digestion,pyrosequencing, fluorescent in situ sequencing (FISSEQ), wobblesequencing, multiplex sequencing, polymerized colony (POLONY) sequencing(see, e.g., US 2012/0270740); nanogrid rolling circle (ROLONY)sequencing (see, e.g., US 2009/0018024), allele-specific oligo ligationassay sequencing, sequencing on an NGS platform, or any suitablesequencing procedure. Non-limiting examples of NGS platforms includesystems from Illumina® (San Diego, Calif.) (e.g., MiSeg™, NextSeg™,HiSeg™, and HiSeq X™), Life Technologies (Carlsbad, Calif.) (e.g., IonTorrent™), and Pacific Biosciences (Menlo Park, Calif.) (e.g., PacBio®RS II).

A location-specific nucleotide sequence (e.g., a barcode) may be atleast 2, at least 3, at least 4, at least 5, at least 6, at least 7, atleast 8, at least 9, at least 10, at least 11, at least 12, at least 13,at least 14, at least 15, at least 16, at least 17, at least 18, atleast 19, at least 20, at least 21, at least 22, at least 23, at least24, at least 25, at least 26, at least 27, at least 28, at least 29, orat least 30 nucleotides in length.

A target-specific nucleotide sequence may be at least 10, at least 11,at least 12, at least 13, at least 14, at least 15, at least 16, atleast 17, at least 18, at least 19, at least 20, at least 21, at least22, at least 23, at least 24, at least 25 nucleotides, at least 26, atleast 27, at least 28, at least 29, at least 30, at least 40, at least50, at least 75, or at least 100 nucleotides in length.

At least one location on a microarray may be further marked with aunique molecular identifier tag. Unique molecular identifiers may beused to quantify growth (e.g., growth of a microorganism colony orreplication of cells at the location). Unique molecular identifiers maybe random nucleotide sequences. Methods using unique molecularidentifiers and examples of unique molecular identifiers have beendescribed in the art, see, e.g., WO 2013/173394, which is incorporatedby reference herein in its entirety. For example, a unique molecularidentifier tag may have the nucleotide sequenceNNNANNNCNNNTNNNGNNNANNNCNNN (SEQ ID NO:1), wherein the Ns (equal randommix of ACGT) create a large encoding space so that each moleculeamplified gets a unique (specific) DNA sequence barcode (4{circumflexover ( )}N barcodes, or 4{circumflex over ( )}21˜4 trillion in thisexample) This sequence can be counted without interference fromamplification bias or other technical problems. The fixed bases in SEQID NO:1 (the A, C, G, T) help with reading the barcode accurately, e.g.,handling indels.

The present disclosure encompasses using location-specific tags tomonitor the presence or amount of more than one target-specificnucleotide sequence in a sample (e.g., multiplexing). At least onelocation on a microarray may be further marked with a second unique tagcomprising a nucleic acid molecule comprising, for example: (i) anamplification primer binding site; (ii) a location-specific nucleotidesequence; and (iii) a target-specific nucleotide sequence.

In some embodiments, a nucleic acid molecule may comprise atarget-specific nucleotide sequence without comprising alocation-specific nucleotide sequence. In certain embodiments, a nucleicacid molecule may comprise a target-specific nucleotide sequence withoutcomprising either a location-specific nucleotide sequence or anamplification binding site sequence. In further embodiments, a nucleicacid molecule may comprise only a target-specific nucleotide sequence.In even further embodiments, a nucleic acid molecule may contain only atarget-specific nucleotide sequence. The target-specific nucleotidesequence may be at least 10, at least 11, at least 12, at least 13, atleast 14, at least 15, at least 16, at least 17, at least 18, at least19, at least 20, at least 21, at least 22, at least 23, at least 24, atleast 25 nucleotides, at least 26, at least 27, at least 28, at least29, at least 30, at least 40, at least 50, at least 75, or at least 100nucleotides in length. In certain embodiments, the target-specificsequence may be the same at every location in the microarray. Additionaltarget-specific nucleotide sequences may be monitored. For example, oneor more locations may be marked with at least 10, at least 25, at least50, at least 75, or at least 100 unique tags, wherein each tag comprisesa target-specific nucleotide sequence that is different from the othertarget-specific nucleotide sequences in the tags at that location.

Any genetic locus of interest may provide a target-specific nucleotidesequence. For example, sequences of bacterial 16S ribosomal RNA (rRNA),18S ribosomal RNA, poly(A) RNA, an RNA polymerase gene, a DNA polymerasegene, the RecA gene, a transposase gene, ribosomal internal transcribedspacer (ITS) sequences, a gene encoding an enzyme, control region DNAsequences, binding site DNA sequences, or a portion of any of thesesequences may serve as a target-specific nucleotide sequence. Adisclosed system, kit, apparatus, or method may use one or more of thebacterial 16S rRNA primers described in Sundquist et al., “BacterialFlora-Typing with Targeted, Chip-Based Pyrosequencing,” 7:108 BMCMicrobiology (2007) and Wang et al., “Conservative Fragments inBacterial 16S rRNA Genes and Primer Design for 16S Ribosomal DNAAmplicons in Metagenomic Studies,” 4:10 PLoS ONE e7401 (2009), each ofwhich is incorporated herein by reference in its entirety.

A sample used in the disclosed apparatuses and methods may comprise aplurality of nucleic acid molecules. A sample may comprise at least oneDNA molecule or at least one RNA molecule. A sample may comprise atleast one nucleic acid molecule formed by restriction enzyme digestion.A sample may comprise at least one cell (e.g., an archaebacterial cell,a eubacterial cell, a fungal cell, a plant cell, and/or an animal cell).A sample may comprise at least one microorganism. A sample may compriseone or more viruses (e.g., a bacteriophage), for which host cells mayneed to be provided. A portion of a sample at a location on a microarraymay be a single cell or a colony grown from a single cell. For example,individual microorganisms or cells may be placed in microwells and theindividual microorganisms or cells may be allowed to divide or replicateso that a colony grows within each microwell that had an individualmicroorganism or cell placed in it. A location on a microarray may thuscontain a single microorganism species or a mixed community ofmicroorganism strains that support one another's growth. A sample maycomprise any suitable dilutant. In non-limiting examples, a samplecomprises soil, sewage, fecal matter, contents of a body cavity, abiological fluid, living organic matter, dead organic matter, amicrobial suspension, naturally-sourced freshwater, drinking water,seawater, wastewater, supercritical carbon dioxide, a mineral, a gas, abuffer, alcohol, an organic solvent, and/or an oil. In some embodiments,a nucleic acid molecule comprising (a) (i) a location-specificnucleotide sequence and (ii) one or more target-specific nucleotidesequences; or (b) one or more target-specific nucleotide sequences(i.e., not comprising a location-specific nucleotide sequence) is placedon at least one location on a microarray before a portion of a sample isplaced at the location. In other embodiments, a nucleic acid moleculecomprising (a) (i) a location-specific nucleotide sequence and (ii) oneor more target-specific nucleotide sequences; or (b) one or moretarget-specific nucleotide sequences (i.e., not comprising alocation-specific nucleotide sequence) is placed on at least onelocation on a microarray after a portion of a sample is placed at thelocation. In one example, a sample or a portion of a sample may beplaced on a microarray and incubated before a nucleic acid moleculecomprising at least one of: (i) a location-specific nucleotide sequenceand (ii) a target-specific nucleotide sequence is placed on themicroarray. In some embodiments, a portion of the portion of a samplemay be removed from at least one location on the microarray and storedin a separate receptacle or the microarray may be split either before orafter the nucleic acid molecules are placed on at least one location onthe microarray.

At least one location-specific tag may comprise a nucleic acid moleculeor a portion of a nucleic acid molecule that is pre-synthesized andplaced at the location by a liquid handling procedure. For instance, aliquid handling procedure may be pipetting, spotting with a solid pin,spotting with a hollow pin, or depositing with an inkjet device. A tagmay be generated at the location using multiple nucleic acid moleculesthat are pre-synthesized separately. At least one tag may comprise anucleic acid molecule that is synthesized at the location by in situsynthesis (e.g., by inkjet printing or by photolithography).

Digital Enumeration of Species

A high density chip device comprised of a surface having high densitymicrowells is described herein. Microbes from a microbiome sample may bediluted and applied to the device such that wells contain approximatelyone microbe per occupied well. The chip then may be incubated such thatthe microbes replicate within the wells. Further, a DNA based locationalindexing system is described herein to determine what species is presentin each well. This indexing system may involve having PCR primerspreloaded into each well that contain addressing barcodes that identifythe well and a primer sequence targeted to a specific genetic element(e.g., 16S) in the microbial genome that provides species information ortargets a desired genetic sequence. After incubation, the microbial DNAis released, the PCR primers amplify the target bacterial DNA region,and the amplicons from the various wells on a chip are pooled and thenmay be read next generation sequencing.

The systems, kits, apparatus, and methodologies described herein may beutilized to perform an absolute count of the number of each microbialspecies or variant in a sample. Each well may represent a digital eventwhich represents the presence of a single microbe in the originaldiluted sample. The locational indexing system may allow a user todetermine what bacterial species is in the well. A unit of measurementmay be “there is a bacterial species in a well” and may be independentof the number of bacteria in the well.

In one example, a mixed sample of microbes includes 50% Species 1, 30%Species 2, and 20% Species 3. The sample is diluted then applied to thechip such that each occupied well has, for the most part, one microbe.The microbe replicates. Note the replication rate may be different fordifferent species. Then, the chip is processed such that the DNA fromthe microbes in the wells is released and the 16S or some other targetsequence is amplified. The DNA amplification products from each well maybe pooled and sequenced using next generation sequencing. The nextgeneration sequencing data may be analyzed to determine, for each well,what species is in each occupied well. Many wells may not be occupied atall. The abundance of each species may be determined by: the totalnumber of wells occupied by each species divided by the total number ofoccupied wells. An absolute abundance determination may be made bymultiplying the % abundance of each species from step by the totalnumber of microbes in the original sample. The sequencing data may becompared to publicly available sequence datasets to determine whatspecies is in each occupied well. For example, ribosomal RNA sequencedata is available in the SILVA rRNA database project described above.Other ribosomal RNA sequence databases include the Ribosomal DatabaseProject, Greengenes, and the GenBank® genetic sequence database, alsodescribed above.

Current methods for estimating the abundance of microbial species in asample involve the use of traditional techniques such as microscopy,staining, selective media, metabolic/physiological screens, andcultivation using petri dishes. These methods are often inaccurate dueto lack of specificity (microscopy, staining, metabolic/physiologicalscreens) or lack of ability to account for all species in a sample(selective media, cultivation) whereby many species do not grow well ordo not grow at all with traditional approaches.

Current molecular methods for determining the relative abundance ofmicrobial species in microbiome samples involve extracting microbial DNAfrom samples, performing PCR amplification of the 16S or some other DNAregion that provide species or other information, then performing nextgeneration sequencing (NGS) on the resulting PCR product. The relativeabundance of each species in the original sample is inferred from therelative frequency of the species specific DNA sequence in the NGS data.There are many examples in the literature of this type of analysis andthis method underpins much microbiome research.

The problem with the current methodology is that it does not control fordifferent numbers of 16S gene that may exist in different microbes, PCRbias whereby sequences from different microbial species may be amplifiedat different rates, and sequencing bias where sequences from differentmicrobial species may be sequenced at different rates. The result isthat there is a lot of uncertainty with respect to the accuracy ofrelative abundance data derived using current methodologies.

The counting of different species may be based on the presence of aspecies in a single well. This is directly related to a single microbefrom the original sample partitioning into the well during loading. OnlyPCR/NGS may be used to identify what microbial species exists in eachwell. The number of sequences identified does not form part of thecalculation. Hence, it does not matter if there is PCR, NGS, or targetsequence copy number variance or bias in the method.

Some embodiments may have applications in microbiome research, microbialproduct discovery and development, clinical diagnostics, and any otherarea where accurate counts of microbial species in a sample arerequired.

Accordingly, some embodiments may provide a much more accuratemeasurement of the relative abundance of each species in a microbiomesample, and the ability to convert this relative abundance measurementinto an absolute abundance or a direct count of each species in theoriginal sample (by accounting for the dilution and/or combining with ameasurement of the total number of microbes in the original sample).Some embodiments may provide new applications for high densitymicrofabricated chips (in addition to cultivation and screening ofmicrobes).

FIG. 18 is a flowchart illustrating a counting method in accordance withsome embodiments. In step 1800, a sample is obtained. In step 1802, atleast one cell is extracted from the obtained sample. In step 1804, atleast one high density microwell array of a microfabricated device orchip is loaded with the at least one extracted cell. Step 1804 mayinclude preparing a cell concentration with the at least one extractedcell, selecting at least one nutrient/media, and/or selecting at leastone membrane. In step 1806, at least a portion of the microwell array issealed with the at least one selected membrane to retain the cellconcentration with the microwells. In step 1808, the chip is incubated.Step 1808 may include selecting a temperature, determining atmosphere(e.g., aerobic or anaerobic), and/or timing incubation). In step 1810,the cultivated cells may be sacrificed for identification. Step 1810 mayinclude PCR, sequencing, and/or various data analytics. In step 1812,information about the sample (e.g., a microbial community structure) maybe assessed and/or determined.

FIG. 19 is a diagram illustrating a counting method in accordance withsome embodiments. Panel 1900 shows examples of complex samples,specifically a microbiome sample 1902 and a soil sample 1904. In Panel1906, at least one cell is extracted from the sample using, for example,the protocol illustrated in FIGS. 5A and 5B. In Panel 1908, the at leastone extracted cell (and any environmental extract and/or dilutant) isloaded on a microfabricated device or chip with at least one highdensity microwell array 1910. Chip 1910 and a reagent cartridge 1912 maybe loaded into an incubator 1914. The reagent may be useful for addingliquid to maintain nutritional requirements for growth and/or variousscreening purposes. Panel 1916 shows the output: sequences and relativeabundance of cultivated cells.

Droplet-Based Platforms

A discrete droplet-based platform may be used to separate, cultivate,and/or screen in much the same way that chips are used. A droplet is ananalog of a microwell serving as a nano- or picoliter vessel. Dropletgeneration methods, especially when combined with cell-sorter-on-a-chiptype instrumentation, may be used to separate out microbes from acomplex environmental sample. Droplet addition may be used to feedmicrobes. Droplet splitting may be used for sequencing or some otherdestructive testing while leaving behind a living sample. All the prepwork necessary for sequencing may be done in droplet format as well.

Some embodiments may be used to get microbes out of a complexenvironment and into droplets. For example, a modular system forgenerating droplets containing cell suspensions may contain one or smallnumbers of cells. The aqueous drops may be suspended in a nonmiscibleliquid keeping them apart from each other and from touching orcontaminating any surfaces. Droplets may be generated at, for example,30 Hz in each microchannel, which translates into millions per day.

A drop-based microfluidic system may encapsulate, manipulate, and/orincubate small drops (e.g., about 30 pL). Cell survival andproliferation is noted to be similar to control experiments in bulksolution. Droplets may be produced at several hundred Hz, meaningmillions of drops can be produced in a few hours. A simple chip-baseddevice may be used to generate droplets and the droplets may beengineered to contain a single cell.

Some embodiments may be used to screen cells in droplets. Fluorescencescreening of droplets post-incubation may be done on-chip and at a rateof, for example, 500 drops per second. Droplets may be flowed through achannel at the focus of an epifluorescence microscope that may beconfigured for a number of different measurements. This may be aparticularly effective way to do screening for metabolites as the localconcentration is quite high on account of being confined to a very smalldroplet.

Some embodiments may be used to sort droplets. Once cells have beenisolated, grown, and/or screened, they may be sorted so that usefulsamples may be retrieved. Droplets may be sorted in an analogous way tothe commonly used FACS machine.

Some embodiments may be used to split droplets. Some embodiments mayrequire the ability to take a sample and split it in order to send oneportion to sequencing (a destructive process) and retain another portionthat is a viable culture. There are a number of different ways to splitdroplets including, but not limited to, constructing T-junctions withcarefully calculated dimensions that result in drops splitting as theyflow by or electrowetting (taking care not to cause cell lysis withvoltages that are too high).

Some embodiments may be used to merge droplets and/or add a reagent to adroplet. For example, long term incubation of cells (e.g., weeks)requires the ability to add liquid to maintain nutritional requirementsfor growth. It also may be useful to be able to add reagents for variousscreening purposes. Droplet screening relies on being able to merge adroplet containing a compound-code with a droplet containing a singlecell. The droplets then may be incubated and/or returned to an assaychip to identify compounds via their codes. This may require the abilityto precisely merge drops on an as-needed basis.

Some embodiments may be used to perform PCR in droplets. PCR may be usedin order to ultimately sequence a specific genetic element (e.g., the16S region) in order to identify microbes. This may be used to determinewhat type of microbe is growing in each well. In a droplet-based systemthis approach may be used to determine what microbe is present in eachdroplet as long as the correct primer sequence is designed to amplifythe right region of the genome.

Some embodiments may be used to sequence DNA out of droplets (e.g.,generated in the PCR step) and/or prepare DNA libraries.

Location Specific Tags for High Density Chips

A high density chip device having a surface with a high density ofmicrowells may be used. Microbes from a microbiome sample may be dilutedand applied to the device such that wells contain approximately onemicrobe per occupied well. The chip may be incubated such that themicrobe replicates within the well and the resulting populationrepresents a single species. A DNA-based locational indexing system maybe used to determine what species is present in each well. This indexingsystem may involve having PCR primers preloaded into each well thatcontain addressing barcodes that identify the well, and a primersequence targeted to a specific genetic element (e.g., 16S in themicrobial genome) that provides species information. After incubationthe microbial DNA may be released, the PCR primers may amplify thetarget bacterial DNA region, and the amplicons from the various wells ona chip may be pooled and then read by next generation sequencing.

The above locational indexing system may involve incorporating adifferent locational code for each well of the microchip, or multiplelocational codes may be incorporated into each well such that the totalnumber of codes required to code a specified number of wells is reduced.For example, if there are 100 wells in a chip it would require 100 codesif there is one code per well. The same chip could be coded with only 20codes if two codes were read from each well (i.e., 10 coding for the xaxis of the grid and 10 coding for the y axis).

An example of a PCR strategy to incorporate two codes per well isprovided in TABLE 2.

TABLE 2 Primers Amplified PCR Products 5′-CODE1- CODE1-TARGETSEQUENCE-TARGETSEQUENCEPRIMER1-3′ CODE 2 3′-TARGETSEQUENCEPRIMER2- CODE2-5′

An example of a PCR strategy to incorporate three codes per wellprovided in TABLE 3.

TABLE 3 Primers Amplified PCR Products 5′-CODE1- CODE1-TARGETSEQUENCE-TARGETSEQUENCEPRIMER1-3′ CODE 2-ADAPTER-CODE3 3′-TARGETSEQUENCEPRIMER2-CODE2-ADAPTER 5′ 3′-ADAPTER′-CODE3′ 5′

Three oligo primers are used to make a single PCR product. Advantages tothis system using two oligos to put a multi-partite barcode on one endof the molecule may include, for example, reducing maximum length ofoligos needed or making extra-long barcodes.

This approach can be generalized to incorporate n barcodes per reaction.The approach can also have different implementations such that thebarcodes are on the same side of the target sequence region. NGSsequencing adaptors may be added, and the full sequence for thepopulation of barcoded PCR products may be read using next generationsequencing.

In another implementation, a fixed code may be added to indicate samplenumber or plate number and allow pooling of multiple samples/plates in arun for two barcodes as shown in TABLE 4.

TABLE 4 Primers Amplified PCR Products 5′-PLATEA-CODE1- PLATEA-CODE1-TARGETSEQUENCEPRIMER1-3′ TARGETSEQUENCE-CODE 2 3′-TARGETSEQUENCEPRIMER2-CODE2-5′

In another implementation, a fixed code may be added to indicate samplenumber or plate number and allow pooling of multiple samples/plates in arun for three barcodes as shown in TABLE 5.

TABLE 5 Primers Amplified PCR Products 5′-PLATEA-CODE1- PLATEA-CODE1-TARGETSEQUENCEPRIMER1-3′ TARGETSEQUENCE-CODE 3′-TARGETSEQUENCEPRIMER2-2-ADAPTER-CODE3 CODE2-ADAPTER 5′ 3′-ADAPTER′-CODE3′ 5′

Note that in all cases the position of the barcode in the sequenceconveys information hence the CODE1, CODE2, and CODE3 barcodes do notnecessarily have to be different from each other in a particular well.

Making oligos and printing chips using a single code coding system arehigh cost. For example, a 10,000 well chip requires 10,000 singlebarcodes and 10,000 separate printing cycles to place those barcodesinto the wells on the chip. If a two-code system is used, thenpotentially only 200 barcodes are required with only 200 printing cyclesto manufacture chips. This represents a significant saving in oligocost, printing time and printing capital investment.

The use of dual barcoded PCR primers, followed by amplification andsequencing analysis, to provide locational data on DNA or DNA containingmoieties randomly partitioned onto a microfabricated chip may have highutility and relatively low cost.

FIG. 20 is a diagram illustrating an indexing system in accordance withsome embodiments. Microwell chip 2000 has N rows and M columns, therebyproducing N×M unique indices. A location of a microwell in chip 2000 maybe considered to have the coordinates (N, M). Each column has a commonreverse primer sequence (e.g., R1, R2, R3, . . . RM), and each row has acommon forward primer sequence (e.g., F1, F2, F3, . . . FN). Forexample, a unique tag targeted to a specific genetic element in, forexample, 16S ribosomal ribonucleic acid (rRNA) may include forwardprimer sequence F515 and reverse primer sequence R806. Following PCR ofchip 2000, the presence of the targeted genetic element may be mappedback to a unique microwell of origin based on the presence of a forwardprimer sequence and a reverse primer sequence. For example, the presenceof F515 and R806 directs a user to the microwell with coordinates (515,806) in chip 2000.

Variability Reduction for PCR Amplification Product Across MicrowellsContaining Bacteria

A DNA-based locational indexing system may be used to determine whatspecies is present in each well. This indexing system may involve havingPCR primers preloaded into each well that contain addressing barcodesthat identify the well, and a primer sequence targeted to a specificgenetic element (e.g. 16S) in the microbial genome that provides speciesinformation. After incubation the microbial DNA may be released, the PCRprimers amplify the target bacterial DNA region, and the amplicons fromthe various wells on a chip are pooled and then read by next generationsequencing.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include limiting amount of PCR primer in thewell during manufacture of the chip such that for the majority ofpossible sample DNA concentrations the amount of PCR primer willlimiting in the DNA amplification reaction, hence the amount of PCRproduct produced will be less variable across wells.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include limiting the number of PCR cycles onthe chip to less than 3 cycles, or less than 5 cycles, or less than 10cycles or less than 15 cycles, or less than 20 cycles or less than 25cycles or less than 30 cycles such that the amount of PCR productproduced will be less variable across wells vs. a full cycle PCRamplification protocol.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include limiting the amount of nucleotides inthe reaction mix so that the number of PCR amplicons produced is a morerelated to the amount of nucleotides than the amount of DNA in theoriginal sample. Microwells with a large amount of target DNA willexhaust the nucleotides early in the cycling process while microwellswith a small amount of target DNA will exhaust the nucleotides later inthe cycling process, but produce around the same amount of amplificationproduct.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include limiting the amount of nutrientavailable to microbes growing in the wells such that cells willreplicate until the media is exhausted then stop replicating.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include placing a dye in each well thatidentifies PCR product such that the signal gets brighter as more PCRproduct is produced. The intensity of the dye during each PCR cycle maybe monitored, and a sample may be taken from the well once the desiredsignal intensity is observed.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include using mixtures of hybridization beadscovered with oligos complementary to each well-specific bar code toselectively hybridize amplified DNA from each well. Once the beads aresaturated unbound DNA may be washed away releasing bound DNA from thebeads. The amount of DNA from each well will then be normalized at thesaturation limit of the beads.

Some embodiments for limiting the variability in the amount of PCRproduct across wells may include incubating chips for a long period oftime such that the fast growing microbes rapidly fill wells and ceasereplicating, and the slower growing microbes gradually fill wells andcease growing once approximately the same number of cells are in thewells

In some embodiments, use of barcoded primers and next generationsequencing (NGS) within the context of the chip format and method may beused to identify which species is growing in which well on the highdensity microchip. When an approximately equal number of bacteria occupyeach microwell in the chip, the signal from each well in the NGS datamay be approximately the same.

For example, in a typical NGS run generating 12 million sequence reads,if 24 chips are sequenced in the run, each having 10,000 microwells, andthere is the same number of bacteria per well, there is on average 50reads per well.

However, different bacteria grow at different rates so it is likely thatsome wells have few bacteria and some wells will have many bacteria.This potentially skews the NGS run so much that the wells with fewbacteria are not detected in the NGS analysis.

Hence, in the example of a typical NGS run generating 12 millionsequence reads, 24 chips are sequenced per run, each having 10,000microwells, half of which have 100 times more bacteria in them than theother half. The probability that the bacteria in the slow growing wellsare detected is markedly reduced. In this case:(10,000×24)/2×100=12,000,000  (1)(10,000×24)/2=120,000  (2)

The low frequency wells are represented at 1% of total. So of 12,000,000reads in an NGS run 120,000 will be from the low frequency wells—i.e.average of 1 read per well.

To minimize the impact of this phenomenon novel methods need to bedeveloped to help equalize the amount of PCR product across wells sothat all wells are detected in the NGS run.

Silicon-Based Microwell Chips for Microbial Isolation, Growth,Screening, and Analysis

A microfabricated device or chip may be composed at least in part ofsilicon instead of or in addition to plastic, glass, and/or polymers toallow for electrical measurements on a well-by-well basis. For example,the walls of each well may be isolated to create microcapacitors. Inanother example, an FET in each well such that the gate surface isexposed to the contents of the well. Instead of a purely silicon-basedchip, thin metal layers may be generated on top of an existing chip byplating, vapor deposition, and/or arc/flame spraying. This may add morefunctionality to a chip, utilize alternate methods of manufacture whichmay be cheaper and/or cleaner, and/or allow miniaturization for handheldand/or portable devices.

Some embodiments may allow for monitoring growth by electricalmeasurement. Impedance monitoring may be applied to measuremicroorganism (e.g., bacterial) growth. For example, impedance across atube containing Escherichia coli (E. coli) is compared to cell countstherefrom in Ur et al., “Impedance Monitoring of Bacterial Activity,”8:1 J. Med. Microbiology 19-28 (1975), which is incorporated herein byreference in its entirety. Measurements may be taken on other types ofbacteria including Pseudomonas, Klebsiella, and Streptococcus todemonstrate the effect is general. Wells may be filled with differentmedia in order to test growth conditions across different formulations.

Some embodiments may allow for screening by electrical measurement.Electrical measurements may be made on a well-by-well basis allowing forscreening. One example would be pH. There are a number of different waysto get a pH-dependent response from the gate of a device in a wellincluding, but not limited to, ISFETs and pH-meters. An array of wellswith embedded pH sensors may determine, electrically, which wellscontain microbes that are producing acidic or basic metabolites. Asimple example is screening for the production of lactic acid fromlactose. Bacteria is diluted out into wells, grown, and then fedlactose. Wells that record a drop in pH contain microbes capable ofmetabolizing lactose into lactic acid.

Some embodiments may allow for electrical measurements of redox probes.Another way to leverage electrical measurements is to look at howbacteria in wells affect a known redox probe. Essentially, a system withwell-defined response may be measured in the presence of bacteria anddeviations from expected behavior may be attributed to the bacterialsamples. A typical redox probe is something like ferricyanide;[Fe(CN)6]3-/4-. The reduction of ferricyanide to ferrocyanide is verywell characterized such that small changes in behavior, particularlyaround electron transfer from the electrodes, are discoverable. Thissystem is “label free” as it detects without having to directly modifythe bacteria themselves.

Antibodies that can recognize microorganisms (e.g., E. coli) may beimmobilized on ITO electrodes. Electron transfer resistance may bemeasured from the electrodes to a ferricyanide containing solution. E.coli binding to the electrode surface increases the resistanceproportional to the concentration of E. coli on the surface. This is oneexample of a family of measurements that may be made to detect specifictypes of organisms or metabolites using redox probes.

Working in silicon (or at least metals or metallized plastics) providesadvantages including, but not limited to, less expensive production ofchips (e.g., by piggybacking on existing technologies); integrateddetection capability allowing small and/or portable versions; additionalmeasuring capabilities not present in other materials (e.g., LCR, CV,etc.); integration of newly discovered chip-based detection modalitiesinto existing devices; and the combination of electrical measurementsand sequencing. These advantages would benefit any customer usinginterferometric detection.

Releasable Barriers to Protect Well-Specific Chemistries on a Chip

FIGS. 21A-21E are diagrams illustrating a chip with well-specificchemistries in accordance with some embodiments. In FIG. 21A, amicrofabricated device or chip is shown with a plurality of microwells.In FIG. 21B, microwell-specific chemistries have been disposed in eachmicrowell of the chip. In FIG. 21C, a sealant has been applied over themicrowell-specific chemistries in each microwell of the chip, therebypreventing interaction of the chemistries with further additions to thewells. In FIG. 21D, samples are loaded, and experiments are performed onthe samples in the microwells. In FIG. 21E, a trigger (e.g., heat)releases the microwell-specific chemistries for interaction with samplesin the wells.

Microwell chips may be manufactured, be cleaned, and/or have surfacestreated. The specific chemistries may be prepared separately and thendeposited into wells by, for example, using a method and/or device thatallows a specific set of chemicals to be directed to a specific well (orwells). A sealant then may be applied to protect the various chemistriesfrom the environment and/or be removed/released/disbursed with somedefined, external trigger.

A microfabricated device or chip may be manufactured to a specificdesign, for example, cleaned and/or surface treated to improve wetting.PCR primers may be printed or pin-spotted into specific wells. The chipmay be allowed to dry, and then a wax layer may be deposited byevaporation from an ethanol solution. Optimal concentration may be about1% v/v. Molten wax may be applied directly or an aqueous or alcohol waxsolution may be sprayed. Alternatively, spin coating or vapor depositionmay be used. Various waxes may be used including, but not limited to,glyceryl stearate with and without polyethylene glycol, cetearylalcohol, 1-hexadecanol, glyceryl ester of stearic acid, ceteareth-20(CAS Registry No. 68439-49-6), and some commercial products including,but not limited to, Lotionpro™ 165 (available from Lotioncrafter®,Eastsound, Wash.) and Polawax™ (available from Croda, Inc., Edison,N.J.). The underlying chemistry later may be released by, for example,heating until the wax melts. For these compositions it will be between50° C. and 70° C. It is important to be low enough not to damage anychemical component or to boil our aqueous solutions.

The key concept is of well-specific chemistry that is walled off fromthe chip until the experimenter triggers release. This method may beused for barcoding in wells, but it also may be applied more broadly toa whole range of different problems. Different chemistries that may beuseful to seal on a chip include, but are not limited to, antibiotics,fluors, dyes, PCR primers, lysis-promoters, antibodies, and/or tests forvarious metabolites. While wax is a good way to seal things that canlater be released by heating, other materials may be used to seal andrelease upon exposure to light, sonication, and/or some other trigger.The advantage of this method over simply adding reagents to the chip isone of control on a well-by-well basis. A similar effect might beachieved by printing chemicals into wells after doing microbialexperiments, but this introduces problems with time (the print run maybe as long as a day) and the fact that it is impossible to expose everywell for the same amount of time if each well is filled individuallyafter the microbes are on the chip. With a release mechanism every wellcan be exposed at the same time. In one example, wax may be depositedonto chips by solvent casting.

Isolated Microwells for Simplicity and/or Controlling Relative Abundance

A high-density chip device may comprise a surface having high-densitymicrowells. Microbes from a microbiome sample, or other cell types, maybe diluted and applied to the device such that wells containapproximately one microbe or cell per occupied well. These microwellsmay be sealed with semi-permeable membranes that allow nutrients todiffuse into the microwells but prevent all or at least some of themicrobes or cells from moving out of the microwells.

A sample of microbes or cells may be prepared and then sealed into achip using an impermeable or only-gas-permeable membrane. No reservoirof liquid sits on top of the chip or membrane and hence only thenutrient in the well at the time of sealing is available to supportgrowth of the microbes or cells in the microwell. Two reasons for thisfeature include: (1) simplicity in construction and workflow as thedevice need not have semi-permeable membranes or reservoirs, nutrientsdo not have to be added, and there is less potential for contamination;and (2) a check on the relative abundance of fast-growers by limitingtheir access to nutrients. For a sample containing some fast-growers andsome slow-growers, the fast-growers will rapidly be resource-limited intheir respective microwells and stop or slow growth while theslow-growers continue to grow. This provides for slow growers to berepresented at a higher relative abundance in the population of microbesacross the chip, compared to the case where the fast growers do not havea limiting amount of nutrient. This becomes important for downstreamprocessing when sequencing everything on a chip. It also provides abetter detection limit for rare species as the rare species are notoutgrown by fast growing species to a point that limits the ability ofthe system to detect them.

Current methods attempt to get all species to grow whether they arefast- or slow-growing by nature. This has the inevitable result thatfast-growers dominate communities and only increase in relativeabundance with time. Many types of downstream analysis such assequencing or fluorescence screening cannot resolve every species in agiven population but only those above a certain limiting relativeabundance. If the goal is to preserve diversity and detect rare species,then the fast-growers need to be limited in some way.

For an example that demonstrates this idea, consider the simple case ofa sample containing two species: one doubles every day and the otherdoubles every week as shown in TABLE 6. If the slow-grower is rare tobegin with, at 5% relative abundance, it soon becomes very rare as bothspecies grow.

TABLE 6 Unlim- Day Day Day Day Day Day ited 0 1 2 3 7 14 Fast 19 38 76152 2432 311296 grower Slow 1 1 1 1 2 3 grower Total 20 39 77 153 2434311299 Rel. ab. 0.950 0.974 0.987 0.993 0.999 1.000 fast Rel. ab. 0.0500.026 0.013 0.007 0.001 0.000 slow

If the fast-growers are limited by competition for nutrition and/orphysical space to grow, then the relative abundance of the slow-growerswill start to increase after some time has elapsed as shown in TABLE 7.

TABLE 7 Day Day Day Day Day Day Limited 0 1 2 3 7 14 Fast grower 19 3850 50 50 50 Slow grower 1 1 1 1 2 3 Total 20 39 51 51 52 53 Rel. ab.fast 0.950 0.974 0.980 0.980 0.962 0.943 Rel. ab. slow 0.050 0.026 0.0200.020 0.038 0.057High Density Microfabricated Arrays for Biobanking Cells

Biobanks are designed to give researchers access to a large number ofsamples from a large population in order to drive certain types ofresearch, such as disease-related biomarker discovery. The current stateof the art in biobanking provides for samples to be stored in tubes orlow-density plate format such as a 96-well or 384-well plate. This workswhen the number of samples to be stored is relatively low in number andthe samples themselves are discrete, isolated populations. Currentapproaches to biobanking become very cumbersome when storing samples,such as microbiome samples, where the number of samples may be high andthe number of different species or variants in each sample may extendfrom hundreds to thousands or many millions per sample. Using currentmethods, a laborious isolation protocol must be implemented to separateout individual species or variants either prior to or subsequent to thestorage step in order to access a desired species or variant.

The systems, kits, apparatus, and methodologies described herein may beapplied to biobank cells, microbes, viruses, and other biologicalentities. A high-density chip device comprised of a surface having highdensity microwells may have thousands, hundreds of thousands, ormillions of microwells per chip. For example, microbes from a microbiomesample (or another biological entity such as a different type of cell ora virus) may be diluted and applied to the device such that wellscontain approximately one microbe per occupied well. The chip then maybe incubated such that the microbe replicates within the well and theresulting population represents a single species. A nucleic acid-basedlocational indexing system may be utilized to determine what species ispresent in each well. This indexing system may involve having PCRprimers preloaded into each well. The PCR primers may contain addressingbarcodes that identify the well, and a primer sequence targeted to aspecific genetic element (e.g., 16S) in the microbial genome thatprovides species information or targets a desired genetic sequence.After incubation the microbial DNA is released, and the PCR primersamplify the target bacterial DNA region. The amplicons from the variouswells on a chip may be pooled and then read by next generationsequencing.

Using high-density microfabricated chips for biobanking provides for amultitude of species or variants within each sample to be stored asseparate populations without the need to implement a laborious isolationprotocol either before or after storage. Using the DNA-based locationalindexing system or a custom assay enables a simpler, generic approach toidentifying genetic signatures or characteristics of the contents ofeach microwell to give information such as, for example, speciesinformation. Additionally, the chip devices provide for an extremelyspace effective method of storing cell isolates. For example, a singlemicroscope slide dimensioned chip with 100,000 wells occupiessubstantially less space that the corresponding traditional storageformats. The chip format also may be useful for properly archiving andcurating samples and/or for managing subject (e.g., patient) informationdatabases by having one chip contain many different samples from asingle subject.

In order to bank cells using this apparatus, cells may be disposedand/or positioned in microwells of the apparatus. The cells in themicrowells may be treated to ameliorate the impact of storage thenplaced in appropriate storage conditions. For example, cells may betreated with agents such as glycerol to ameliorate the impact offreezing. Then the chip may be placed in appropriate storage conditionssuch as a freezer. The cells may be dehydrated, lyophilized, and/orfreeze dried, and the chip may be placed in appropriate conditions tosafeguard the dried cells. Additional structures may be added to thechip to further enhance its utility as a storage device. For example, amembrane or another structural element may be placed on top of the chipto seal at least some of the wells prior to storage.

A chip may be loaded with cells such that a portion of microwells on thechip are occupied by approximately one cell each. The chip is incubatedto allow for replication of cells. The chip and its contents aresubstantially replicated, and either the original chip or the copy chipis used to identify the cells or species or gene signatures present ineach well of the chip (by, e.g., using the locational indexing systemdescribed above). The chip is treated and/or stored in appropriateconditions. The replication step and/or the identification step may takeplace after storage rather than before storage.

One or more cells from each strain of a pre-existing set of isolatedstrains may be disposed into separate microwells on a chip. The positionof the microwell into which each strain or cell type was placed may berecorded, and the chip may be treated and/or stored in appropriateconditions.

A version of the chip may be created in which preservative chemistry issequestered underneath a wax barrier in each well. Isolates may beallowed to grow sealed up inside a chip and then preserved at a laterdate by heat-induced release of the preservatives before banking.

Such apparatus may be used to store/biobank mixed microbiome samplessuch as microbiome samples from soil, human gut, seawater, oral cavity,skin, etc. A chip may be used to store other types of biologicalentities such as fungi, archaebacteria, human cells (includingreproductive cells), animal cells, and viruses.

The DNA locational indexing system may be used across all biologicalentity types to generate information regarding the content of each well.An entire chip may be screened for desired activity using custom assayssuch as antibody- or substrate-based assays. For example, a chip withbanked populations of T cells may be screened for a particularimmunological activity.

In one illustrative example, human stool microbiome samples may becollected from study participants. The stool microbes from eachindividual may be biobanked on chips to maintain both a record of thatindividual's microbiome as well as a sample of the microbiome to use asa source of target microbes at a later date. In another example, mixedpopulations of T cells or other immunological cells may be sampled fromindividuals during clinical or research studies or as part of atherapeutic workflow (e.g., cell therapy using ex vivo treated cells).In yet another example, soil biomes may be stored in conjunction withseed banking.

High Resolution Picking

A high accuracy/precision picking apparatus or system may be designed toexecute various picking functions from and/or to microwells on amicrofabricated chip described above. A target substrate or chip may bea microscope slide format (approximately 25 mm×75 mm×1 mm) withinjection-molded features on one surface. Microwells may be arranged ina grid pattern with about 4-8 mm well-free edge around the edges of thechip. Well size and spacing may be determined based on pickercapability. Microwells may be square with a size from about 25 μm toabout 200 μm along each edge and spacing in from about 25 μm to about100 μm between well edges. Microwells may be circular or hexagonalinstead. Well depths may be from about 25 μm to about 100 μm. Forexample, a 75 mm×25 mm slide with a 7 mm edge, 100 μm square wells with100 micron edge-to-edge spacing will have about 16,775 microwells.

A high accuracy/precision picking system may be designed to executevarious picking functions from and/or to portions of a membranecorresponding to microwells on a microfabricated chip, as describedabove. A membrane may be a thin sheet that has previously been used toseal growing bacteria into microwells. When peeled off the chip themembrane may retain an imprint of the microwell array as well as asample of bacteria on its surface after separation from the chip. Thus,the peeled membrane may act as a replicate of the bacteria growing inthe chip.

A high resolution picker may receive data input from a user. The inputmay include at least one pair of chip microwell coordinates such thatthe picker picks from and/or to the at least one input pair ofcoordinates. A sterilization routine may be performed between cycles. Ahigh resolution picker may be capable of operating in an anaerobicchamber.

A high resolution picker system may receive a chip and align the pickerwith the chip, for example, using fiducial markers and/or referencewells. The picker may pick, for example, cells growing in microwells onthe chip into, for example, 96- or 384-well plates containing growthmedia. The picker may include a single picking pin or a plurality ofpicking pins.

A high resolution picker system may receive a membrane and align thepicker with the membrane, for example, using reference well marks on themembrane. The picker may pick, for example, cells from the membraneinto, for example, 96- or 384-well plates containing growth media. Thepicking pin(s) may have a different shape (e.g., mushroom-shaped) and/orsurface (e.g., texture) for picking from a membrane. The system also mayinclude one or more mechanisms (e.g., a floating pin and/or vacuum) tohold and/or flatten the membrane.

A high resolution picker system may enable chip replication via achip-to-chip transfer. The picker may receive and align a first chipbased on fiducial markers and/or reference wells. The picker also mayreceive and align a second chip based on fiducial markers and/orreference wells. The picker may transfer, for example, cells growing inmicrowells on the first chip to microwells on the second chip.

A high throughput system for automatically picking a target species of aplurality of species of at least one biological entity cultivated in amicrofabricated device may include a port for receiving themicrofabricated device. The microfabricated device defines a highdensity array of microwells. Each microwell of the high density array ofmicrowells is configured to isolate and cultivate at least one speciesof the at least one biological entity and includes at least one tag of aplurality of unique tags. Each tag of the plurality of unique tagsincludes a nucleic acid molecule, which includes a target-specificnucleotide sequence for annealing to the at least one biological entityand a location-specific nucleotide sequence correlating to at least onemicrowell of the high density array of microwells. The system alsoincludes a high-resolution picking apparatus with at least oneprotrusion for picking the at least one biological entity from at leastone microwell of the high density array of microwells. The systemfurther includes an input device for receiving an indication of at leastone target-specific nucleotide sequence and at least one processorcommunicatively coupled to the input device and the high-resolutionpicking apparatus. The at least one processor acquires the indication ofthe at least one target-specific nucleotide sequence from the inputdevice, compares the at least one target-specific nucleotide sequence tothe plurality of unique tags, determines at least one microwell of thehigh density array of microwells including the target species based onthe comparison, and controls the high-resolution picking apparatus topick the at least one biological entity from the at least one determinedmicrowell of the high density array of microwells.

A high throughput system is disclosed for automatically picking a targetspecies of a plurality of species of at least one biological entitycultivated in a microfabricated device. The microfabricated devicedefines a high density array of microwells, each microwell of the highdensity array of microwells being associated with at least one uniqueprimer of the plurality of unique primers. The system includes a portfor receiving a membrane removed from the microfabricated device, themembrane having sealed each microwell of the high density array ofmicrowells to retain the at least one biological entity in the highdensity array of microwells, such that portions of the at least onebiological entity corresponding to the high density array of microwellsremain attached to the membrane following removal of the membrane. Thesystem also includes a high-resolution picking apparatus including atleast one protrusion for picking the at least one biological entity fromat least one membrane location corresponding to at least one microwellof the high density array of microwells, an input device for receivingan indication of at least one target-specific nucleotide sequenceassociated with the target species, and at least one processorcommunicatively coupled to the input device and the high-resolutionpicking apparatus. The at least one processor acquires the indication ofthe at least one target-specific nucleotide sequence from the inputdevice, compares the at least one target-specific nucleotide sequence tothe plurality of unique tags, determines at least one membrane locationcorresponding to at least one microwell of the high density array ofmicrowells comprising the target species based on the comparison, andcontrols the high-resolution picking apparatus to pick the portions ofthe at least one biological entity from the at least one determinedmembrane location.

The above-described embodiments can be implemented in any of numerousways. For example, embodiments may be implemented using hardware,software or a combination thereof. When implemented in software, thesoftware code can be executed on any suitable processor or collection ofprocessors, whether provided in a single computer or distributed amongmultiple computers.

Further, it should be appreciated that a computer may be embodied in anyof a number of forms, such as a rack-mounted computer, a desktopcomputer, a laptop computer, or a tablet computer. Additionally, acomputer may be embedded in a device not generally regarded as acomputer but with suitable processing capabilities, including a PersonalDigital Assistant (PDA), a smart phone or any other suitable portable orfixed electronic device.

Also, a computer may have one or more input and output devices. Thesedevices can be used, among other things, to present a user interface.Examples of output devices that can be used to provide a user interfaceinclude printers or display screens for visual presentation of outputand speakers or other sound generating devices for audible presentationof output. Examples of input devices that can be used for a userinterface include keyboards, and pointing devices, such as mice, touchpads, and digitizing tablets. As another example, a computer may receiveinput information through speech recognition or in other audible format.

Such computers may be interconnected by one or more networks in anysuitable form, including a local area network or a wide area network,such as an enterprise network, and intelligent network (IN) or theInternet. Such networks may be based on any suitable technology and mayoperate according to any suitable protocol and may include wirelessnetworks, wired networks or fiber optic networks.

The various methods or processes outlined herein may be coded assoftware that is executable on one or more processors that employ anyone of a variety of operating systems or platforms. Additionally, suchsoftware may be written using any of a number of suitable programminglanguages and/or programming or scripting tools, and also may becompiled as executable machine language code or intermediate code thatis executed on a framework or virtual machine.

Magnetic Beads

In some embodiments, the systems, kits, apparatus, and methods describedabove may utilize magnetic beads. For example, magnetic beads may beused to transfer a portion of the contents of a microwell from a firstchip into a corresponding microwell on a duplicate second chip, therebysubstantially replicating the first chip. By substantially replicatingthe first chip (or source chip), either the original or the copy maysupport many different types of downstream analysis while the otherremaining chip may be used for a different purpose such as the recoveryof viable cells. Further, such magnetic beads-mediated transfer can becarried out in a highly parallel fashion in that all the microwells maybe processed at the same time. This is particularly advantageouscompared to sequential duplication methods when the density of the arrayof microwells on a chip is large (e.g., thousands or millions).

Thus, in accordance with an aspect of the present disclosure, methods oftransferring material (or contents) from a first microfabricated device(or chip) to a second microfabricated device (or chip) is provided. Thefirst microfabricated device and the second microfabricated deviceinclude a first array of microwells and a second array of microwells,respectively. In some embodiments, each microwell of the first array ofmicrowells can be aligned with a corresponding microwell of the secondarray of microwells (e.g., the first and second microfabricated devicemay have the same microwell pattern or configuration). For short, thevarious transfer methods described in the present disclosure utilizingmagnetic beads are referred generally as “bead transfer” methods or“bead mediated transfer” methods. The material/contents of a microwellon the source chip may be transferred to a corresponding microwell onthe target chip with the movement of one or more magnetic beads viaphysical adsorption, absorption, nonspecific binding, or specificbinding, etc.

The portion of contents or material transferred may comprise, forexample, at least one of solute, reaction product, a liquid, and abiological entity (for example, one or more cells or viruses, a cellsurface, (e.g., membrane or wall), a metabolite, a vitamin, a hormone, aneurotransmitter, an antibody, an amino acid, an enzyme, a peptide,protein, a saccharide, ATP, a lipid, a nucleoside, a nucleotide, anucleic acid (e.g., DNA or RNA), etc.).

In some embodiments, the method comprises: preparing the firstmicrofabricated device such that at least one microwell of the firstarray of microwells includes a material of interest and at least onemagnetic bead; positioning the second microfabricated device relative tothe first microfabricate chip such that the at least one microwell ofthe first array of microwells of the first microfabricated device isaligned with at least one microwell of the second array of microwells ofthe second microfabricated device; and applying a magnetic field so asto move the at least one magnetic bead contained in the at least onemicrowell of the first array of microwells into the at least onemicrowell of the second array of microwells, whereby at least a portionof the material of interest in the at least one microwell of the firstarray of microwells is transferred to the at least one microwell of thesecond array of microwells.

In other embodiments, the method comprises: loading at least onemagnetic bead into at least one microwell of the first array ofmicrowells; incubating the first microfabricated device to grow aplurality of cells in at least one microwell of the first array ofmicrowells; positioning the second microfabricated device relative tothe first microfabricated device such that the at least one microwell ofthe first array of microwells of the first microfabricated device isaligned with at least one microwell of the second array of microwells ofthe second microfabricated device; and applying a magnetic field so asto move the at least one magnetic bead contained in the at least onemicrowell of the first array of microwells into the at least onemicrowell of the second array of microwells, whereby at least one cellfrom the plurality of cells in the at least one microwell of the firstarray of microwells is transferred to the at least one microwell of thesecond array of microwells.

In some embodiments, microbes are grown in the array of microwells ofthe first chip, then the chip is substantially replicated using magneticbeads to transfer a portion of the microbes to the second chip. In someembodiments, chemical reactions are conducted in the array of microwellsof the first chip, then the first chip is substantially replicated usingmagnetic beads to transfer a portion of the reaction product to thesecond chip.

FIG. 22 is an illustrative diagram illustrating a general transferprocess using magnetic beads in accordance with some embodiments. First,a first microfabricated device 2210 with an array of microwells 2215(which comprises at least one magnetic bead and at least one material ofinterest) is aligned with a second microfabricated device 2220 with aduplicate array of microwells. The upper surface 2211 of the firstdevice and the upper surface 2221 of the second device are facing eachother in the alignment such that the openings of the microwells aredirectly opposing each other to allow transfer. In some embodiments, theoriginal array of microwells includes multiple magnetic beads and/ormaterials of interest. In further embodiments, one microwell can includemultiple magnetic beads and/or materials of interest. A magnetic fieldcan be applied, e.g., by using a magnet 2230 positioned along the backside of the second device 2220 such that the magnetic beads 2223 aredrawn from the microwells of the first device to move into the alignedmicrowells of the second device 2220. As a result, at least a portion ofthe contents of a first microwell in the first device adheres to or isotherwise carried or caused to move by the magnetic beads to the secondmicrowell in the second device. Although it is shown the second device2220 is blank (i.e., with no loaded content), it is understood that itmay contain culture media or other content as desired. Further, both thefirst device 2210 and the second device 2220 can be used to cultivatemore cells and/or perform any downstream experiments or assays asdesired.

FIGS. 23A-23C are images illustrating a transfer of material by puttingmagnetic beads into a chip containing bacteria and then aligning a freshchip above it and pulling the beads across with a magnet in accordancewith some embodiments. FIG. 23A shows the two chips prior to overlay,FIG. 23B shows the two chips aligned, and FIG. 23C shows a magnet ispositioned over the chips to pull the magnetic beads out of the bottomchip and into the top chip.

FIG. 24A is a microscopic image of a source chip containing magneticbeads; FIG. 24B is a microscopic image of a destination chip (which isinitially empty) after transfer of magnetic beads. As used herein,“magnetic beads” (or “magnetic nanoparticles”) refer to beads comprisingparamagnetic or superparamagnetic cores (such as iron oxide) that areresponsive to an applied magnetic field. The surface of a magnetic beadmay be roughened/textured. The magnetic beads may also be overcoated ormodified with small molecules, biocompatible polymers, peptides,proteins, etc., to enhance binding or transfer. For example, a magneticbead may be configured to capture biological entities (e.g., entraininga solvent with a lectin, recognizing a molecule with an antibody, and/orselectively hybridizing a nucleic acid with an oligonucleotide), and/ora biological entity may be induced to grow on a surface of a magneticbead. In the examples of the present disclosure, two kinds of magneticbeads were tested. Thermo Fisher magnetic beads (Dynabeads® M-270Carboxylic Acid)) with a diameter of about 2.8 μM (which are sphericalsuperparamagnetic core encapsulated with a polymer shell) and SpherotechInc's sphere carboxyl magnetic beads (CM-80-10) with a diameter of 8.79μm, which are coated be with polymer and modified with surface carboxylgroups.

Magnetic beads can be introduced to the microwells of the firstmicrofabricated device immediately prior to the bead transfer (e.g.,after incubation), loaded before or with the initial contents of themicrowells, or added at any time therebetween. Additional sets ofmagnetic beads may be loaded into the microwells of the first chip forrepeated transfer to make additional copies of the first chip atdifferent times.

The second (or destination) chip may have reagents and/or mediapre-loaded into its microwells prior to the transfer of material fromthe source chip. In some embodiments, the reagents and/or media aredried in the microwells or sealed in the microwells with a releasablebarrier (e.g., wax). Reagents and/or media may not need to be sealed inmicrowells because of capillary action; that is, surface tension andadhesive forces between liquid and the walls of a microwell act tomaintain the liquid in the microwell despite external forces likegravity.

There are different ways the magnetic beads can be loaded on amicrofabricated device. For example, magnetic beads can be loaded onto achip (i.e., into the microwells of the chip) in a beads solution (orsuspension) which includes a carrier solvent. The carrier solvent isthen evaporated. This chip can be stored to be used for a future date,ready for loading materials of interest (e.g., microbial cells, othercells, etc.), sealing with a membrane, if desired or necessary, andincubating the chip as normal with the beads remaining inside themicrowells. Before loading the magnetic beads, the microfabricated chipcan first be surface treated to make it hydrophilic. A magnet can beplaced under the microfabricated chip while loading the magnetic beadsto draw the magnetic beads down into the microwells. Any magnetic beadsthat are not loaded into the microwells and remain on the surfacebetween microwells can be removed by applying and peeling off a tape.

Alternatively, magnetic beads can be pre-mixed with a material/sample(such as a microbial isolate), and then the mixture is loaded on themicrofabricated chip. For example, the chip can be first surface treatedto make it hydrophilic, then magnetic beads (in solution or suspension)can be added to the sample cells to make a mixture, which is then loadedonto the chip. A magnet is placed under the chip while the mixture isloaded onto the chip to draw the beads down into the microwells. Themicrowells can then be sealed for further cultivation, if desired. Andfurther alternatively, magnetic beads solution or its mixture with asample can be printed into individual microwells using a dropletprinter.

The microfabricated chip loaded with the samples and magnetic beads canthen be incubated to cultivate or grow cells (or to perform experimentsor assays as desired). Testing results of a few known strains showedthat the cell growth was unimpeded by the presence of beads (which areaggregated at the bottom of the wells due to magnetic pull duringloading), and this can be expected for other samples. There may bemicrobial species that prefer to grow on surfaces, in which case theadditional surface area provided by the magnetic beads may enhancegrowth. It is possible to functionalize the beads to have differentsurface chemistries that would be used to promote or reduce certaintypes of growth. For example, some microbes are known to grow better onaminated surfaces. In such cases, the magnetic beads can be chemicallyaltered to have an amine surface group and promote growth.

For the transfer of magnetic beads from one chip to another (so that aportion of the contents in the original or source microwells are“dragged” across into the target or destination microwells on the newchip), preferably, some but not all contents in the original microwellare transferred. For example, at least one cell is transferred to thenew chip, and at least one cell is left behind, so that after anotherperiod of growth both chips can have similar contents in sufficientamounts for picking, PCR, screening, or other assays as needed.

In some cases, the beads transfer allows some of the liquid in theoriginal microwells, which has the cells suspended in it, to be carriedby the magnetic beads across into the other chip. In the case ofmultiple beads in one microwell, particularly smaller ones, a largeamount of liquid can be transported by the magnetic beads. The presenceof multiple or a cluster of magnetic beads in one microwell alsoenhances the magnetic pull.

It is important that during the beads transfer, the relative locationsof the magnetic beads are preserved. For example, magnetic beads fromone location on the chip {row 3, column 2} could be transferred to thesecond chip in the same place {row 3, column 2}, and so on, thusretaining the relative locations of microwell contents in the secondchip. In order to keep the locational information, the chips must bepositioned such that the source and target microwells are perfectlyaligned and facing each other. For this step to work properly, the chipsthemselves need to be made to very exacting standards, and thedimensions of the chips and microwells on them do not vary and thermaldistortion is minimal.

To facilitate alignment, the chips are aligned with the aid of amicroscope. FIGS. 25A-25C show an example how two chips are aligned.FIG. 25A shows that a first chip is fixed to the microscope stage. FIG.26B shows a second chip is placed above the first chip with the focus ofthe microscope between the two chips. This produces a slightly blurredimage. FIG. 25C show the two chips are aligned after the top chip ismaneuvered until all the microwells are aligned. Different orientationsof the two chips can be used, e.g., the beads can be transferred fromtop to bottom, bottom to top, or left to right. The effects of beaddensity appear minimal. A slight advantage might be gained going fromthe top chip to the bottom chip in the case of extremely dense beads.

The magnet used for beads transfer can be either a permanent magnet oran electromagnet. The ability to switch the magnetic field off and oncan be helpful. The magnetic force required for the bead transfer candepend on many relevant factors such as the size of the magnetic beads,the sample to be transferred, etc. The relative force required can beestimated following the computational methods outlined inBiomicrofluidics 7, 014104 (2013); doi: 10.1063/1.4788922. For the beadstransfer from chip to chip, an air gap can be left between the twochips, or a liquid layer can be placed between the chips. The latterhelps to remove interfaces between the microwells because the interfacemakes it harder to transfer beads using magnetic field. The liquid layercan be an aqueous layer such as media or buffer, an alcohol, or asolvent or oil immiscible with water, or any other liquid.

It is important to minimize cross contamination from the bead transferprocess. As shown in FIGS. 26A and 26B, it is desired that the beadsfrom different closed-spaced microwells of the source chip aretransferred to the aligned microwells of the destination chip. FIGS. 26Cand 26D illustrate a scenario where magnetic beads from differentmicrowells of the source chip are mixed in microwells of the destinationchip. This can result in undesired cross contamination. To reduce suchcross contamination, a barrier layer for preventing cross-contaminationsuch as oil can be added between the chips.

The transferred material/content can be further used to grow and/orconduct other experiments or assays. It has been shown that bacteriacells transferred across to the new chip continued to grow. In oneexample, E. coli was then pipetted onto a first chip (whose microwellshave been loaded with magnetic beads) and grown overnight. The next daybacterial growth was observed in all the wells. See FIG. 27A. The firstchip was blotted with paper to remove some liquid from the wells andensure the space between wells was dry. Ethanol was used to wipe acrossthe top of the first chip to ensure no contact contamination occurredbetween chips. A new chip whose microwells had been loaded with mediawas aligned against the first chip and a magnet was used to pull themagnetic beads across over a few seconds. After the beads weretransferred out, very few remain on the original chip as shown in FIG.27B. After a period of growth overnight, grown E. coli were easilyobserved in the microwells of the new chip. See FIG. 27C. This test wasrepeated successfully for different well dimensions. Most of the beadswere transferred to the new chip where bacteria were grown up overnight.

One potential use for chip splitting by magnetic bead transfer is tohave one chip to get sequencing data from while keeping a copy for laterretrieval of live isolates based on the sequencing results. To get thesequencing data, PCR can be run on a chip in order to build up ampliconsfor sequencing. Prior to PCR, the magnetic beads can be transferred overto another chip, and the PCR is run on the original chip with reducednumber of magnetic beads. The PCR can also be run on the new chip nowcontaining the transferred beads. The presence of the magnetic beadsdoes not inhibit the on-chip PCR. In a test, different concentrations ofbeads were loaded from 0 up to 2400 per well. E. coli gDNA was mixedwith PCR buffer, loaded onto the chips, and the array of microwells onthe chips were sealed with Qiagen vapor lock. The results shown in FIG.28 indicate the on-chip PCR amplicon is present in all of the testedchips, and that there the beads do not interfere the PCR even at thehighest concentration of beads.

Tests showed that the presence of the magnetic beads in the microwellsdo not hinder the growth of bacterial cells. In an example, E. colibacteria were grown in the presence of magnetic beads on a first chip,and a portion of the bacteria were transferred over to a new chip, wherethey were grown more and an on-chip PCR process was performed, theresults of which were checked for gDNA as a proxy for growth. Briefly,the on-chip PCR was performed as follows. Magnetic beads were loadedinto the chip at some specified amount (240 beads/microwell and 2400beads/microwell). A magnet was placed underneath the chip to hold themagnetic beads down while the bacteria or gDNA and other reagents wereadded into the microwells. PCR master mix containing 16S rRNA V4 primerswas pipetted onto the surface of the chip. A reservoir was placed overthe microwells on the chip and mineral oil added to avoid PCR bufferevaporation. On-chip PCR was performed using a thermocycling programwith the following parameters: 96° C. 10 min, followed by 39 cycles of60° C. for 2 min, 98° C. for 40 seconds, 60° C. for 2 min, then hold at10° C. After the PCR, the chip was taken out, the amplicons were washedoff the chip by PBS and the 16S rRNA V4 amplicon extracted with theQiagen Qiaquick kit. In a more complex run (the results of which isshown in Lane 1 in FIG. 29), beads were loaded on a chip, then bacteriaand media. The chip was sealed and grown for a while. Later, thebacteria were transferred to another chip by magnet and run through thePCR process. FIG. 29 shows that the bacteria growth was not affected bythe presence of the magnetic beads during the steps of the aboveworkflow. The different lanes in FIG. 29 represent the results of thefollowing experiments:

-   -   1. Bacteria grown on a chip with 240 beads per microwell,        transferred by a magnet to a new chip, allowed to grow for        another day, then run through PCR to give a gDNA band in the        appropriate place.    -   2. Negative control (no cells or gDNA, only beads and relevant        chemistry for amplification). No bands.    -   3. E. coli bacteria loaded on a chip and run through PCR with no        beads present.    -   4. gDNA loaded on a chip and run through PCR with no beads        present    -   5. gDNA loaded on a chip and run through PCR with 2400 beads per        well present.    -   6. gDNA loaded on a chip and run through PCR with 240 beads per        well present.

In another example, a mixture of Acinetobacter calcoaceticus, Serratiamarcescens, and Staphylococcys warneri was added to two chips with 240magnetic beads/well. The chips were incubated overnight at 30° C. andthen the magnetic beads were transferred to new chips. These new chipswere allowed to grow overnight at 30° C. An on-chip PCR was run, theresults of which are shown in FIG. 30. The band indicating a 16Samplicon shows clearly for both chips.

CONCLUSION

While various inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto, inventive embodiments may be practicedotherwise than as specifically described and claimed. Inventiveembodiments of the present disclosure are directed to each individualfeature, system, article, material, kit, and/or method described herein.In addition, any combination of two or more such features, systems,articles, materials, kits, and/or methods, if such features, systems,articles, materials, kits, and/or methods are not mutually inconsistent,is included within the inventive scope of the present disclosure.

Also, various inventive concepts may be embodied as one or more methods,of which an example has been provided. The acts performed as part of themethod may be ordered in any suitable way. Accordingly, embodiments maybe constructed in which acts are performed in an order different thanillustrated, which may include performing some acts simultaneously, eventhough shown as sequential acts in illustrative embodiments.

All publications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

What is claimed is:
 1. A method of transferring material from a firstmicrofabricated device comprising an upper surface including a firstarray of microwells to a second microfabricated device comprising anupper surface including a second array of microwells, the methodcomprising: loading at least one magnetic bead into at least onemicrowell of the first array of microwells; incubating the firstmicrofabricated device to cultivate a plurality of cells in at least onemicrowell of the first array of microwells; positioning the secondmicrofabricated device relative to the first microfabricated device suchthat the at least one microwell of the first array of microwells of thefirst microfabricated device is aligned with at least one microwell ofthe second array of microwells of the second microfabricated device,wherein positioning the second microfabricated device relative to thefirst microfabricated device comprises positioning the upper surface ofthe second microfabricated device opposing the upper surface of thefirst microfabricated device; and applying a magnetic field so as tomove the at least one magnetic bead contained in the at least onemicrowell of the first array of microwells into the at least onemicrowell of the second array of microwells, whereby at least one cellfrom the plurality of cells in the at least one microwell of the firstarray of microwells is transferred to the at least one microwell of thesecond array of microwells.
 2. The method of claim 1, wherein applyingthe magnetic field comprises using a permanent magnet.
 3. The method ofclaim 1, wherein applying the magnetic field comprises using anelectromagnet.
 4. The method of claim 1, further comprising: prior toincubating the first microfabricated device, preparing the firstmicrofabricated device such that at least one microwell of the firstarray of microwells includes at least one cell and at least one magneticbead, wherein incubating the first microfabricated device comprisescultivating a plurality of cells in the at least one microwell of thefirst microfabricated device from the at least one cell.
 5. The methodof claim 4, wherein preparing the first microfabricated devicecomprises: loading a magnetic bead solution including a solvent and atleast one magnetic bead into the at least one microwell; and loading atleast one cell into the at least one microwell.
 6. The method of claim5, further comprising: applying a magnet to the first microfabricateddevice so that the at least one magnetic bead is drawn to the inside ofthe at least one microwell; and allowing evaporation of the solvent. 7.The method of claim 4, wherein preparing the first microfabricateddevice comprises: loading into the at least one microwell a samplesolution including at least one magnetic bead and at least one cell. 8.The method of claim 4, wherein preparing the first microfabricateddevice comprises: applying a membrane to seal the at least onemicrowell.
 9. The method of claim 1, wherein positioning the secondmicrofabricated device relative to the first microfabricated devicecomprises positioning the upper surface of the second microfabricateddevice apart from the upper surface of the first microfabricated device.10. The method of claim 1, wherein positioning the secondmicrofabricated device relative to the first microfabricated devicecomprises positioning the upper surface of the second microfabricateddevice in contact with the upper surface of the first microfabricateddevice.
 11. The method of claim 1, further comprising: prior to applyingthe magnetic field, applying a liquid layer on the at least onemicrowell of the first array of microwells of the first microfabricateddevice.
 12. The method of claim 11, wherein the liquid layer is an oillayer.
 13. The method of claim 11, wherein the liquid layer is anaqueous layer.
 14. The method of claim 1, wherein the surface density ofthe first array of microwells is at least 150 microwells per cm², atleast 250 microwells per cm², at least 400 microwells per cm², at least500 microwells per cm², at least 750 microwells per cm², at least 1,000microwells per cm², at least 2,500 microwells per cm², at least 5,000microwells per cm², at least 7,500 microwells per cm², at least 10,000microwells per cm², at least 50,000 microwells per cm², at least 100,000microwells per cm², or at least 160,000 microwells per cm².
 15. Themethod of claim 1, wherein each microwell of the first array ofmicrowells of the first microfabricated device has a diameter of fromabout 5 μm to about 500 μm, from about 10 μm to about 300 μm, or fromabout 20 μm to about 200 μm.
 16. A method of transferring material froma first microfabricated device comprising an upper surface including afirst array of microwells to a second microfabricated device comprisingan upper surface including a second array of microwells, the methodcomprising: preparing the first microfabricated device such that atleast one microwell of the first array of microwells includes a materialof interest and at least one magnetic bead; positioning the secondmicrofabricated device relative to the first microfabricated device suchthat the at least one microwell of the first array of microwells of thefirst microfabricated device is aligned with at least one microwell ofthe second array of microwells of the second microfabricated device,wherein positioning the second microfabricated device relative to thefirst microfabricated device comprises positioning the upper surface ofthe second microfabricated device opposing the upper surface of thefirst microfabricated device; and applying a magnetic field so as tomove the at least one magnetic bead contained in the at least onemicrowell of the first array of microwells into the at least onemicrowell of the second array of microwells, whereby at least a portionof the material of interest in the at least one microwell of the firstarray of microwells is transferred to the at least one microwell of thesecond array of microwells.
 17. The method of claim 16, wherein thematerial of interest is a biological entity.
 18. The method of claim 16,wherein the material of interest comprises a plurality of cells.
 19. Themethod of claim 16, wherein preparing the first microfabricated devicecomprises: providing the at least one microwell of the first array ofmicrowells with at least one cell and at least one magnetic bead; andprior to applying the magnetic field, incubating the firstmicrofabricated device to grow a plurality of cells from the provided atleast one cell in the at least one microwell of the firstmicrofabricated device.
 20. The method of claim 19, wherein providingthe at least one microwell of the first array of microwells with atleast one cell and at least one magnetic bead comprises: loading amagnetic bead solution including a solvent and at least one magneticbead into the at least one microwell; and loading at least one cell intothe at least one microwell.
 21. The method of claim 19, whereinproviding the at least one microwell of the first array of microwellswith at least one cell and at least one magnetic bead comprises: loadinginto the at least one microwell a sample solution including at least onemagnetic bead and at least one cell.
 22. The method of claim 16, whereinthe surface density of the first array of microwells is at least 150microwells per cm², at least 250 microwells per cm², at least 400microwells per cm², at least 500 microwells per cm², at least 750microwells per cm², at least 1,000 microwells per cm², at least 2,500microwells per cm², at least 5,000 microwells per cm², at least 7,500microwells per cm², at least 10,000 microwells per cm², at least 50,000microwells per cm², at least 100,000 microwells per cm², or at least160,000 microwells per cm².
 23. The method of claim 16, wherein eachmicrowell of the first array of microwells of the first microfabricateddevice has a diameter of from about 5 μm to about 500 μm, from about 10μm to about 300 μm, or from about 20 μm to about 200 μm.
 24. A method oftransferring material from a first microfabricated device including afirst array of microwells, at least one microwell of which comprises atleast one magnetic bead, to a second microfabricated device including asecond array of microwells, the method comprising: providing a materialof interest into the at least one microwell which comprises the at leastone magnetic bead; positioning the second microfabricated devicerelative to the first microfabricated device such that the at least onemicrowell of the first array of microwells of the first microfabricateddevice is aligned with at least one microwell of the second array ofmicrowells of the second microfabricated device; and applying a magneticfield so as to move the at least one magnetic bead contained in the atleast one microwell of the first array of microwells into the at leastone microwell of the second array of microwells, whereby at least aportion of the material of interest in the at least one microwell of thefirst array of microwells is transferred to the at least one microwellof the second array of microwells.
 25. A method of transferring materialfrom a first microfabricated device comprising an upper surfaceincluding a first array of microwells, at least one microwell of whichcomprises at least one magnetic bead and a material of interest, to asecond microfabricated device comprising an upper surface including asecond array of microwells, the method comprising: positioning thesecond microfabricated device relative to the first microfabricateddevice such that the at least one microwell of the first array ofmicrowells of the first microfabricated device is aligned with at leastone microwell of the second array of microwells of the secondmicrofabricated device, wherein positioning the second microfabricateddevice relative to the first microfabricated device comprisespositioning the upper surface of the second microfabricated deviceopposing the upper surface of the first microfabricated device; applyinga magnetic field so as to move the at least one magnetic bead containedin the at least one microwell of the first array of microwells into theat least one microwell of the second array of microwells, whereby atleast a portion of the material of interest in the at least onemicrowell of the first array of microwells is transferred to the atleast one microwell of the second array of microwells.